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Tytuł:
Magnetoelectric Effect of Cr_{2}O_{3}
Autorzy:
Latacz, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1968405.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.80.+q
75.50.Ee
Opis:
A formula for the temperature dependent magnetoelectric susceptibility of Cr$\text{}_{2}$O$\text{}_{3}$ is obtained using the method of renormalized spin waves of Nagai and compared with the formula in random phase approximation. The three coefficients a$\text{}^{g}$, a$\text{}^{LS}$, and a$\text{}^{J}$ which respectively represent the change in the g-factor, in the crystal field splitting and in the exchange integral due to the electric field parallel to the easy axis, are determined by comparing the theoretical with experimental susceptibility curves, as well as the antiferromagnetic resonance shift.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 733-735
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetism of Higher Borides
Autorzy:
Mori, T.
Powiązania:
https://bibliotekanauki.pl/articles/1813620.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Je
75.50.Ee
Opis:
Magnetism of borides which contain the $B_{12}$ icosahedra as a structural building block are attracting increasing interest since they exhibit unexpectedly strong magnetic interactions, despite being magnetically dilute f-electron insulators. The magnetic behavior among the different compounds has also been found to be diverse. The f-electron dependence of magnetic B_{12} icosahedra borides is compared, and found to be different from conventional mechanisms. The $TbB_{25}$ system is also investigated further and the transition is assigned to a typical antiferromagnetic transition.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 231-234
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric effect in antiferromagnetic half-Heusler alloy DyNiSb
Autorzy:
Synoradzki, K.
Ciesielski, K.
Kaczorowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/1050664.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Sg
Opis:
The low-temperature magnetic, thermal and magnetocaloric properties of the half-Heusler compound DyNiSb were studied on polycrystalline samples. The temperature variations of the magnetization and the heat capacity revealed a phase transition from paramagnetic to antiferromagnetic state at the Néel temperature T_{N} = 3.1 K. The compound exhibits normal and inverse magnetocaloric effect with the isothermal magnetic entropy change reaching 5.2 J/(kg K) at 4.8 K for a magnetic field change of 3 T. The estimated refrigerant capacity is about 58 J/kg.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 691-693
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of DyTe
Autorzy:
Pokrzywnicki, S.
Duczmal, M.
Pawlak, L.
Nenkov, K. A.
Powiązania:
https://bibliotekanauki.pl/articles/1964659.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Cr
Opis:
Dysprosium monotelluride is a metallic substance with one valence electron per formula unit belonging to the conduction band. It crystallizes in the defected NaCl-type structure (a= 0.6070 nm) with cation deficiency in the metal sublattice. AC and DC susceptibilities exhibit a maximum at 15 K and a second maximum at higher temperatures which position is field dependent.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 351-354
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinks in One-Dimensional Two-Sublattice Antiferromagnet with Biquadratic Exchange Interaction
Autorzy:
Baryakhtar, I. V.
Powiązania:
https://bibliotekanauki.pl/articles/1930590.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Gb
75.50.Ee
Opis:
Nonlinear dynamics of an antiferromagnet in continuum approximation on the basis of the Heisenberg Hamiltonian for two sublattices with biquadratic exchange interaction in each sublattice and single ion anisotropy is considered. Exact particular solution, describing the stationary kink movement, including the region v ≥ c, is found.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 399-403
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antiferromagnetism and Superconductivity in Three-Band Hubbard Model
Autorzy:
Dutka, J.
Oleś, A.
Powiązania:
https://bibliotekanauki.pl/articles/1930567.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
74.20.-z
Opis:
We determined the phase diagram of the three-band model for CuO$\text{}_{2}$ planes of high temperature superconductors with an attractive interoxygen interaction U$\text{}_{pp}$. The found magnetic moments of 0.47µ$\text{}_{B}$ in the undoped system, the disappearance of antiferromagnetic order at the doping of δ ≈ 0.06 hole per CuO$\text{}_{2}$ unit, as well as the enhanced tendency to superconductivity with the decreasing value of charge-transfer gap, are in good agreement with the experimental findings.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 323-327
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Layer-Type Compounds TlGdS$\text{}_{2}$ and TlGdSe$\text{}_{2}$
Autorzy:
Duczmal, M.
Pawlak, L.
Pokrzywnicki, S.
Powiązania:
https://bibliotekanauki.pl/articles/2013695.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Cr
Opis:
Ternary thallium lanthanide dichalcogenides TlLnX$\text{}_{2}$ (X = S, Se, or Te; Ln = lanthanide, except Ce and Pr) crystallize in the rhombohedral structure of α-NaFeO$\text{}_{2}$ type ($R\overline{3}m$). Their crystal lattice consists of the layers of Ln$\text{}^{3+}$ ions separated by three layers of the non-magnetic ions (-Ln-X-Tl-X-Ln-). The magnetization was measured in the field range 0-14 T. The molecular field constants λ$\text{}_{m}$ were estimated by fitting the Brillouin function to the experimental magnetization plots. The difference between the λ$\text{}_{m}$ values for the thallium gadolinium sulphide and the selenide corresponds to the different character of Gd-S and Gd-Se bonds and gives rise to the different J$\text{}_{1}$ and J$\text{}_{2}$ exchange integrals.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 839-842
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pressure Influence on Magnetic Properties of TbNiAl
Autorzy:
Javorský, P.
Prchal, J.
Klicpera, M.
Kaštil, J.
Míšek, M.
Powiązania:
https://bibliotekanauki.pl/articles/1368753.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.-m
Opis:
We have investigated the effect of hydrostatic pressure on magnetic properties of TbNiAl, crystallizing in hexagonal ZrNiAl-type structure. TbNiAl orders antiferromagnetically below $T_{N}$=45 K and undergoes further magnetic phase transition to another AF phase at $T_{1}$=23 K. The magnetic field of $B_{c}$ ≅ 0.3 T applied along the c-axis at 2 K leads to the transition to ferromagnetic order. By applying the hydrostatic pressure, both $T_{N}$ and $T_{1}$ remain almost unaffected whereas $B_{c}$ shows a strong increase. The hydrostatic pressure stabilizes the antiferromagnetic state which can be related to development of structural parameters.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 280-281
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Role of the Surface Energy for the Formation of the Domain Structure at Magnetoelastic Phase Transition
Autorzy:
Gomonaj, H. V.
Loktev, V. M.
Powiązania:
https://bibliotekanauki.pl/articles/2013067.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.60.Ch
Opis:
The formation of the domain structure during magnetic ordering in the pure antiferromagnet with the rotational (non-180°) domains can be treated as thermodynamically preferable if the free energy of the sample is minimized with the account of surface energy. The analogy between the role of magnetostatic energy in ferromagnets and surface energy of antiferromagnet is traced. The behavior of the domain structure and macroscopic strain tensor in the external magnetic field is investigated.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 459-462
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Study of Magnetocaloric Effect in Dipolar Magnet $KEr(MoO_4)_2$
Autorzy:
Hanko, J.
Orendáč, M.
Kajňaková, M.
Orendáčová, A.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813812.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Ee
Opis:
We report on magnetothermodynamic properties of single crystal $KEr(MoO_4)_2$ which were investigated from nominally 0.4 K to 20 K in magnetic fields up to 4 T. Using the available specific heat data the diagram of temperature and magnetic field dependence of the total entropy was constructed. Predictions for temperature dependences of the relative temperature variations during the adiabatic demagnetization and the entropy variation during the isothermal demagnetization were calculated from the specific heat data. The obtained results suggest that unlike common refrigerants, in $KEr(MoO_4)_2$ the quantities describing magnetic cooling remain nearly constant in the temperature range 2-10 K.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 465-468
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Diagram of $TmB_4$ Probed by AC Calorimetry
Autorzy:
Kačmarčík, J.
Pribulová, Z.
Gabáni, S.
Samuely, P.
Siemensmeyer, K.
Shitsevalova, N.
Flachbart, K.
Powiązania:
https://bibliotekanauki.pl/articles/1534368.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.50.Ee
Opis:
TmB_4 is a frustrated system based on the Shastry-Sutherland lattice that exhibits complex magnetic properties. In this contribution the magnetic field B vs. temperature T phase diagram of $TmB_4$ has been studied by ultrasensitive AC calorimetry in the temperature range between 2.9 and 12 K and in magnetic fields up to 8 T. Apart from already known phases our measurements have recognized several new phase transitions suggesting that the phase diagram of $TmB_4$ is even more complex and deserves further studies.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 903-904
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Magnon Spectrum of Antiferromagnetically Aligned Bilayer Films
Autorzy:
Puszkarski, H.
Kołodziejczak, B.
Akjouj, A.
Djafari-Rouhani, B.
Dobrzynski, L.
Powiązania:
https://bibliotekanauki.pl/articles/1929330.pdf
Data publikacji:
1993-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.70.-i
75.50.Ee
Opis:
We deal with spin-wave propagation in two antiferromagnetically aligned sublayers forming one bilayer film owing to the antiferromagnetic exchange coupling assumed to exist at the film interface. We get the following picture: as the spin wave traverses the interface, the creation of a spin-reversal in the one sublayer becomes an annihilation in the other sublayer. This feature is expressed by the non-conventional type of normalization condition of the spin-wave amplitudes.
Źródło:
Acta Physica Polonica A; 1993, 83, 5; 677-683
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Pressure on Magnetic States of Easy-Plane Antiferromagnets
Autorzy:
Mitsay, Yu. N.
Fridman, Yu. A.
Bairamalieva, G. A.
Alexeev, C. N.
Kochmański, M. S.
Powiązania:
https://bibliotekanauki.pl/articles/1964223.pdf
Data publikacji:
1997-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.50.Ee
Opis:
The phase H-P-β diagram of an easy-plane strongly anisotropic antiferromagnet is studied. It is shown that in such a system a realization of the phase with the nonmagnetic order parameter, the so-called quadruple phase, is possible. The realization of this phase is caused by several purely quantum effects, moreover the mechanism of its appearance differs in principle from that of the antiferromagnet or ferromagnet. The possibility of the disappearance of the angular phase (the so-called quadruple ferromagnetic phase) is also shown.
Źródło:
Acta Physica Polonica A; 1997, 91, 6; 1111-1120
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetoelastic and Optical Studies of Low Temperature Magnetic Relaxation in Rare-Earth Orthoaluminates with Ising Ions
Autorzy:
Krynetskii, I.
Popkov, A.
Borowiec, M. T.
Szymczak, H.
Zayarnyuk, T.
Powiązania:
https://bibliotekanauki.pl/articles/2013724.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Gb
75.50.Ee
Opis:
The new class of magnetic materials with low temperature magnetic relaxation was studied. It was evidenced that the crystal DyAlO$\text{}_{3}$ with antiferromagnetically ordered high anisotropy rare-earth ions showed an exponential magnetic relaxation. For the first time low temperature magnetic relaxation was investigated by means of magnetostriction and rare-earth optical absorption spectra instead of standard magnetization measurements. The possible mesoscopic nature of tunneling process was suggested.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 889-892
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependence of Magnetic Inelastic Neutron Scattering in Mn(12%Ge) Alloy
Autorzy:
Jankowska-Kisielińska, J.
Mikke, K.
Milczarek, J. J.
Hennion, B.
Udovenko, V. A.
Powiązania:
https://bibliotekanauki.pl/articles/1956523.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Ds
75.50.Ee
Opis:
A systematic study of temperature dependence of magnetic inelastic neutron scattering for itinerant antiferromagnet Mn(12%Ge) is presented. At low temperatures the experimental data are well described in terms of damped spin waves. This description becomes insufficient at least 150 K below T$\text{}_{N}$. In the temperature range 200-400 K the integrated intensity of distribution for energy transfer 13 THz increases by one third and the shape of the deconvoluted neutron scattering cross-section changes. These changes suggest that ca. 200 K below T$\text{}_{N}$ an additional contribution to the inelastic neutron scattering starts to appear and that its origin is different from spin waves.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 483-486
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Study of the Magnetocaloric Effect in the Two-Dimensional Quantum System $Cu(tn)Cl_2$
Autorzy:
Baranová, L.
Tarasenko, R.
Orendáčová, A.
Orendáč, M.
Pavlík, V.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1368656.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Sg
Opis:
Magnetocaloric studies of a two-dimensional antiferromagnet $Cu(tn)Cl_{2}$ (tn=1,3-diaminopropane=$C_3H_{10}N_2)$ have been performed by adiabatic magnetization and demagnetization measurements, in the temperature range from 0.2 to 4 K and magnetic fields up to 2 T. The compound represents an S=1/2 spatially anisotropic triangular-lattice antiferromagnet. The magnetocaloric measurements were focused at the identification of the phase transition to the magnetically ordered state which was not indicated in the previous specific heat studies. Furthermore, the interplay of the magnetic-field induced easy-plane anisotropy and the intrinsic spin anisotropy present in the studied system should manifest in low magnetic fields. The obtained results of the magnetocaloric experiments of $Cu(tn)Cl_{2}$ indicate a double crossover from the normal to inverse magnetocaloric effect (MCE). The first crossover from the normal to inverse MCE occurring at about 0.3 K can be attributed to the competition of the aforementioned anisotropies. The second crossover from the inverse to normal MCE observed at about 2.2 K might be ascribed to the formation of spin vortices stabilized by the easy-plane anisotropy introduced by magnetic field.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 256-257
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Study of S=1/2 Low-Dimensional Heisenberg Antiferromagnet $[Cu\text{(phen)}(H_2O)_2]SO_4$
Autorzy:
Sedláková, L.
Orendáč, M.
Kajňaková, M.
Orendáčová, A.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813815.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Ee
Opis:
We present the experimental study of magnetocaloric effect on powder sample $[Cu\text{(phen)}(H_2O)_2]SO_4$ (phen = phenantroline = $C_{12}H_8N_2$) in the temperature range from nominally 0.2 K to 4 K and in magnetic fields up to 2 T. The values of total entropy were extracted from the experimental data obtained by adiabatic demagnetization. The comparison was performed with the temperature dependence of the entropy for S=1/2 paramagnet calculated at selected magnetic fields. The deviations observed below 0.6 T were attributed to internal field mediated by exchange coupling. In addition, the temperature response observed in $[Cu\text{(phen)}(H_2O)_2]SO_4$ revealed very short relaxation time below 1 K. The comparison of the behavior observed at the end of the demagnetization in $[Cu\text{(phen)}(H_2O)_2]SO_4$ and other systems suggests that the magnetocaloric effect can serve as an alternative tool for studying slow magnetic relaxation.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 473-476
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Ordering in $ErFe_{0.3}Ge_{2}$ and $ErNi_{0.65}Ge_{2}$ Compounds
Autorzy:
Penc, B.
Arulraj, A.
Kaczorowski, D.
Szytuła, A.
Wawrzyńska, E.
Powiązania:
https://bibliotekanauki.pl/articles/1538339.pdf
Data publikacji:
2010-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Lp
75.50.Ee
Opis:
The magnetic ordering in $ErFe_{0.3}Ge_{2}$ and $ErNi_{0.65}Ge_{2}$ compounds crystallizing in the orthorhombic structure of the $CeNiSi_{2}$-type has been investigated by neutron diffraction and magnetic measurements. The Er magnetic moments have been found to order antiferromagnetically below 2.5 K in $ErFe_{0.3}Ge_{2}$ and 2.3 K in $ErNi_{0.65}Ge_{2}$. The magnetic structure of the former compound can be described by the propagation vector k = (0.044(1), 0, 0.384(1)). The Er magnetic moments are aligned along the a-axis and alternate with the sequence ++- in the unit cell. At 1.5 K they are equal to 5.9(1) $μ_{B}$. In contrast, the magnetic unit cell of $ErNi_{0.65}Ge_{2}$ has been established to be equal to the chemical one. The magnetic moments in this compound are arranged in a collinear manner pointing along the a-axis with the sequence +-+-. The Er moment value measured at 1.5 K is 2.90(8) $μ_{B}$.
Źródło:
Acta Physica Polonica A; 2010, 117, 4; 595-598
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crystal Structure and Magnetic Properties of $Mn_{1-x}Gd_{x}Se$ Solid Solutions
Autorzy:
Aplesnin, S.
Galyas, A.
Demidenko, O.
Makovetskii, G.
Panasevich, A.
Yanushkevich, K.
Powiązania:
https://bibliotekanauki.pl/articles/1385679.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.Dk
75.50.Ee
Opis:
The synthesis of polycrystalline $Mn_{1-x}Gd_{x}Se$ solid solutions is carried out by solid state reaction method followed by quenching from the temperature of 1370 K. The X-ray diffraction studies realized at 300 K revealed that the structure of the single phase samples in the 0 < x < 0.15 concentration range is identified on base a face centered cubic crystal cell of Fm3m space group. The heating of the solid solutions to 900 K does not affect on the magnetic susceptibility as the dependences is identical to the measurements in the "heating-cooling" regime. Comparing the research results of magnetic properties of the $Mn_{1-x}Gd_{x}Se$ solid solutions with those of $Mn_{1-x}Gd_{x}S$ solid solutions, we can conclude that substitution of manganese ions by gadolinium in manganese selenide lead to more changes in the basic magnetic characteristics than in manganese sulfide.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 371-373
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neutron and EPR Study of $Cu(tn)Cl_{2}$ - a Two-Dimensional Spatially Anisotropic Triangular-Lattice Antiferromagnet
Autorzy:
Tarasenko, R.
Orendáčová, A.
Čižmár, E.
Maťaš, S.
Orendáč, M.
Zeleňák, V.
Pavlík, V.
Siemensmeyer, K.
Zvyagin, S.
Wosnitza, J.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1368516.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.50.Ee
Opis:
We have studied the temperature dependence of the lattice parameters and the influence of spin anisotropy on the electron paramagnetic spectra of $Cu(tn)Cl_2$, an S=1/2 quasi-two-dimensional spatially-anisotropic triangular-lattice Heisenberg antiferromagnet. The variation of the resonance fields with temperature reflects the presence of an easy-plane exchange anisotropy with $J_{z}$/$J_{x,y}$<1 and g-factor anisotropy, $g_{z}$/$g_{x,y}$>1.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 232-233
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bulk and Local Magnetic Susceptibility of $ErB_{12}$
Autorzy:
Bogach, A.
Bogomolov, L.
Glushkov, V.
Demishev, S.
Sluchanko, D.
Sluchanko, N.
Shitsevalova, N.
Levchenko, A.
Filipov, V.
Flachbart, K.
Siemensmeyer, K.
Powiązania:
https://bibliotekanauki.pl/articles/1813645.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Eb
75.50.Ee
Opis:
High precision measurements of magnetoresistance Δρ/ρ = f(T,H) and magnetization M(T,H) were carried out on single crystals of rare-earth dodecaboride $ErB_{12}$ at temperatures in the interval 1.8-30 K in magnetic fields up to 70 kOe. The high accuracy of the experiments allowed us to perform numerical differentiation and analyze quantitatively the behavior of the derivative d(Δρ/ρ)/dH = f(T,H) and of the magnetic susceptibility χ(T,H) = dM/dH in paramagnetic and magnetically ordered (antiferromagnetic, $T_N$ ≈ 6.7 K and $T_M$ ≈ 5.85 K) phases of $ErB_{12}$. It was shown that negative magnetoresistance anomalies observed in present study in paramagnetic state of $ErB_{12}$ may be consistently interpreted in the framework of a simple relation between resistivity and magnetization -Δρ/ρ ~ $M^2$.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 271-274
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phonon Drag and Magnetic Anomalies of Thermopower in $RB_{12}$ (R = Ho, Er, Tm, Lu)
Autorzy:
Glushkov, V.
Demishev, S.
Ignatov, M.
Khayrullin, E.
Sluchanko, N.
Shitsevalov, N.
Levchenko, A.
Filipov, V.
Flachbart, K.
Siemensmeyer, K.
Powiązania:
https://bibliotekanauki.pl/articles/1813647.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Jf
75.50.Ee
Opis:
High precision measurements of the Seebeck coefficient S(T) were carried out on the single crystals of $RB_{12}$ (R = Ho, Er, Tm, Lu) at temperatures 2-300 K. It was shown that the effects of phonon drag result from vibrations of rare earth ions ($ħω_E$≈10-33 meV) in the rigid framework structure of the $B_{12}$ clusters and determine the main contribution to thermopower at intermediate temperatures (30-300 K). The correlated behavior of transport parameters favors the appreciable enhancement of spin fluctuations in the sequence of magnetic compounds $(HoB_{12}-TmB_{12})$ when approaching to the valence instability state in $YbB_{12}$. The giant increase in S(T) detected in the vicinity of the Néel temperature $T_N$ for $HoB_{12},$ $ErB_{12},$ and $TmB_{12}$ seems to result from the density of states renormalization caused by antiferromagnetic ordering.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 275-278
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Physical properties study of the CeOsGa₄ compound
Autorzy:
Sondezi, B.
Strydom, A.
Powiązania:
https://bibliotekanauki.pl/articles/1047645.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.50.Cc
75.40.-s
Opis:
A polycrystalline sample of CeOsGa₄ was prepared by arc-melting stoichiometric quantities of high purity elements of 4N and greater, in an arc furnace. The data was confirmed to crystallize in an orthorhombic structure, with a space group Pmma (Number 51). Measurements of the magnetic susceptibility showed a distinct anomaly around T_{o} = 3.8 K, while the high temperature data (above 100 K) obeys Curie-Weiss law. The calculated effective moment of 2.44 μ_{B}, was obtained, which was a bit less than the theoretical moment for a Ce³⁺ ion of 2.54 μ_{B}. Magnetization data at T=2 K depicts that CeOsGa₄ does not saturate up to applied magnetic field of 7 T, while the data measured at 9 K indicates that the compound is purely paramagnetic at that temperature. The low temperature specific heat data is characterized by an anomaly at T_{o} = 3.8 K confirming the χ(T) data. Electrical resistivity shows a metallic behaviour at high temperatures with a deviation at low temperatures, signalling the cooperative behaviour which results to ordering. In this work we present the initial studies of the physical properties measurements performed on this compound.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 398-400
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Transition Metal Molybdates
Autorzy:
Konieczny, P.
Pełka, R.
Grzesiak-Nowak, M.
Szymańska, A.
Łasocha, W.
Wasiutyński, T.
Powiązania:
https://bibliotekanauki.pl/articles/1368631.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Xx
75.50.Ee
75.50.-y
Opis:
Two examples of transition metal molybdates were studied with the use of X-ray diffraction and DC magnetometry techniques. First compound, copper dimolybdate trihydrate $CuMo_{2}O_{7}$·$3H_{2}O$ contains 2D layers. The second one is fibrillar cobalt trimolybdate octahydrate $CoMo_{3}O_{10}$·$8H_{2}O$. Both compounds exhibit paramagnetic behaviour at room temperature. However, in the first one copper ions form dimers linked by oxygen bridges, in which exchange interactions between two localized spin states occur. The second compound consists of isolated cobalt ions in the octahedral surroundings, resulting in magnetic properties deviating from the Curie law.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 250-251
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Phase Diagram of the Second-Type Antiferromagnet
Autorzy:
Balcerzak, T.
Radomska, A.
Powiązania:
https://bibliotekanauki.pl/articles/2013394.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.-b
75.50.Ee
75.50.Pp
Opis:
We investigate theoretically the phase diagrams of the second-type antiferromagnet with the fcc structure. Besides the nearest-neighbour and next-nearest-neighbour exchange interactions, the biquadratic and long-range dipolar terms are taken into account. The results can be useful to discuss the phase diagram of europium telluride under external pressure.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 775-778
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calculations of EuTe Magnetic Phase Diagram for External Pressure
Autorzy:
Radomska, A.
Balcerzak, T.
Powiązania:
https://bibliotekanauki.pl/articles/2014065.pdf
Data publikacji:
2000-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.-b
75.50.Pp
75.50.Ee
Opis:
The magnetic phase diagram of europium telluride, EuTe, under external high pressure is theoretically investigated. Besides nearest-neighbour and next-nearest-neighbour exchange interactions, the long-range dipolar and biquadratic interactions are taken into account. The functional dependences of these interactions on the lattice constant are proposed. The calculated Néel and Curie temperatures are compared with the experimental data. Two new phases, antiferrimagnetic and ferrimagnetic, have been found at a high pressure and low temperatures.
Źródło:
Acta Physica Polonica A; 2000, 98, 1-2; 83-91
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ordered Phases and Magnetic Excitations in Doped Manganites
Autorzy:
Sikora, O.
Oleś, A.M.
Powiązania:
https://bibliotekanauki.pl/articles/2038394.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.30.Ds
75.50.Ee
Opis:
We present theoretical models concerning magnetic and charge ordering in half-doped manganites. The new approach to microscopic description of this group of compounds, taking into consideration the oxygen degrees of freedom, is discussed. The spin wave dispersion relations are shown both in the model of effective spins on Mn ions and in the new approach when two Mn ions form a large effective spin S=7/2.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 659-664
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polaron States in a CuO Chain
Autorzy:
Bieniasz, K.
Oleś, A.
Powiązania:
https://bibliotekanauki.pl/articles/1385209.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.Di
75.10.Pq
75.50.Ee
Opis:
We introduce a one-dimensional model for a CuO chain, with holes and S=1/2 spins localized in $3d_{x²-y²}$ orbitals, and p_σ oxygen orbitals without holes in the ground state. We consider a single hole doped at an oxygen site and study its propagation by spin-flip processes. We develop the Green function method and treat the hole-spin coupling in the self-consistent Born approximation, similar to that successfully used to study polarons in the regular t-J model. We present an analytical solution of the problem and investigate whether the numerical integration is a good approximation to this solution.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 269-271
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Small Antiferromagnetic Spin Systems: Just beyond the Rotational Band Model
Autorzy:
Florek, W.
Kaliszan, L.
Powiązania:
https://bibliotekanauki.pl/articles/1385535.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.50.Ee
75.50.Xx
Opis:
Two systems of spins s=1/2 with the Heisenberg interactions are investigated: (i) an equilateral trapezoid and (ii) a regular hexagon. Both cases are compared with the corresponding sublattice Hamiltonians to determine splitting and mixing of energy levels with a given total spin of sublattices. It is shown that small modifications of the Hamiltonian parameters may significantly change (magnetic) properties of the eigenstates, especially probability of finding system in a state with determined value of the sublattice total spin.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 330-332
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oscillating Antiferromagnetism of Ultrathin EuTe Layers
Autorzy:
Wilamowski, Z.
Springholz, G.
Svrcek, V.
Jantsch, W.
Powiązania:
https://bibliotekanauki.pl/articles/1968444.pdf
Data publikacji:
1997-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.50.Ee
76.50.+g
Opis:
We study magnetic resonance on EuTe/PbTe superlattices. Analysis of the magnetic dipole anisotropy in the superlattices and of the EPR amplitude of isolated Eu ions in the PbTe wells shows that the diffusion at interfaces is very small. The real thickness of EuTe can be evaluated with an accuracy better than one monolayer. Since for EuTe layers thicker than 2 monolayers there is no difference in the character of the antiferromagnetic resonance observed for even and odd numbers of monolayers, we conclude that there is no static magnetization of the antiferromagnetic sublattices. Nevertheless, long range antiferromagnetic order is clearly evident.
Źródło:
Acta Physica Polonica A; 1997, 92, 5; 1051-1054
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Frustration in Some Magnetic Compounds
Autorzy:
Szytuła, A.
Gondek, Ł.
Penc, B.
Hernandez-Velasco, J.
Powiązania:
https://bibliotekanauki.pl/articles/2038386.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Nr
75.25.+z
75.50.Ee
Opis:
In the paper the results of the powder neutron diffraction measurements of RAuIn (R = Ce, Tb, Dy, and Er) and ZnFe$\text{}_{2}$O$\text{}_{4}$ compounds at low temperatures are presented. For the RAuIn compounds, which crystallize in the hexagonal ZrNiAl-type structure, the rare-earth moments lie in the ab-plane and form a typical triangle non-collinear structure. ZnFe$\text{}_{2}$O$\text{}_{4}$ has the normal spinel structure in which the Fe$\text{}^{3+}$ ions occupy the B sites, forming the corner-shared tetrahedra of the Fe spins. At low temperatures experimental data indicate the coexistence of the long-range and the short-range magnetic order. The obtained results suggest that the important factor which influences the magnetic ordering in these compounds is geometrical frustration of magnetic moments.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 583-591
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemical Potential Derivative as Hallmark for Phase Transitions
Autorzy:
Pietruszka, M.
Matlak, M.
Powiązania:
https://bibliotekanauki.pl/articles/2011158.pdf
Data publikacji:
1999-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.-i
75.40.Cx
75.50.Ee
Opis:
We study antiferromagnetic properties of the two-band extended s-f model with fluctuating valence in the context of two mutually bound new effects of chemical potential critical behaviour, as well as of critical electron redistribution. In order to exemplify both phenomena we build phase diagrams of the system displaying the dependence of the critical Néel temperatures (T$\text{}_{N}$) of the system versus 4f (5f) level positions. The phase diagram consists of two different areas corresponding to antiferromagnetic and paramagnetic phases. We plot the magnetizations and the correlation functions of the system as functions of temperature. Next, we investigate the temperature dependence of the relative average occupation numbers Δn$\text{}^{f(d)}$ and the chemical potential Δμ for a given 4f (5f) level position E$\text{}_{f}$. Plotting this quantities along the E$\text{}_{f}$ cross-section lines we observe small (of the order of 10$\text{}^{-4}$-10$\text{}^{-3}$) but well localized kinks exactly at the Néel temperature T$\text{}_{N}$. Last but not least, we plot the first derivative of the chemical potential dμ/dT which, as it shows clearly visible jumps at T$\text{}_{N}$, may turn out to be very accurate and sensitive (auxiliary) tool to find critical temperatures of the considered system. Moreover, we plot the difference μ$\text{}_{AF}$-μ$\text{}_{PARA}$ where we subtract a chemical potential value of a reference paramagnetic sample from the actual value of the antiferromagnetic system. Also in this case we report the observation of discontinuous change in slope at T$\text{}_{N}$. Our observations can be extended to point out to a new practical possibility of how to find experimentally the critical temperatures of the antiferromagnetic systems exclusively from the chemical potential measurements. We expect that the same type of measurement, according to our recent and present results, would also apply to all types of critical phenomena in real solids.
Źródło:
Acta Physica Polonica A; 1999, 96, 6; 725-732
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Semiconductor-Antiferromagnet Superlattices
Autorzy:
Wilamowski, Z.
Buczko, R.
Jantsch, W.
Ludwig, M.
Springholz, G.
Powiązania:
https://bibliotekanauki.pl/articles/1952426.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.50.Pp
76.50.+g
Opis:
Magnetic resonance investigations of ultra-thin antiferromagnetic EuTe layers show a specific behaviour in the quasi-2D antiferromagnetic ordering: (i) an anisotropy of the critical broadening, (ii) a substantial increase in the Néel temperature and (iii) an anisotropic shift of the resonance frequency which diverges at the Néel point. The results show that exchange coupling is stronger in quasi-2D than in 3D antiferromagnetic samples and that correlation of spin chains aligned in the perpendicular direction occurs already well above the Néel point.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 973-976
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Highly Degenerated Ground States in Some Rings Modeled by the Ising Spins with Competing Interactions
Autorzy:
Florek, W.
Antkowiak, M.
Kamieniarz, G.
Jaśniewicz-Pacer, K.
Powiązania:
https://bibliotekanauki.pl/articles/1030746.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.50.Ee
75.50.Xx
Opis:
We discuss three Ising ring systems with competing interactions which are analogs of quantum systems and we show that they exhibit similar properties. In particular, the archetypal system of three antiferromagnetically coupled spins s has two magnetically degenerated ground states with |M|=s, when 0
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 411-413
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Structures of Ho_5Rh_4Ge_{10}
Autorzy:
Szytuła, A.
Penc, B.
Hofmann, M.
Sikora, W.
Powiązania:
https://bibliotekanauki.pl/articles/1399030.pdf
Data publikacji:
2013-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.-j
75.47.Pq
75.50.Ee
Opis:
A powder diffraction measurement of $Ho_5Rh_4Ge_{10}$ is reported. This compound crystallizes in the tetragonal $Sc_5Co_4Si_{10}$-type structure (space group P4/mbm) in which the Ho atoms occupy three different sites. The neutron diffraction measurements indicate antiferromagnetic order with the Néel temperature $T_{N}$=7 K. Below $T_{N}$ an additional phase transition at 4.5 K connected with the change of the magnetic structure is observed. The Ho moments in 4(h) site form collinear order up to T_{N} while moments at 2(a) site form sine modulated structure. Determined experimentally magnetic structures are compared to the results of symmetry analysis.
Źródło:
Acta Physica Polonica A; 2013, 124, 6; 1002-1004
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantum Heisenberg Antiferromagnet on Frustrated Bilayer Lattice in Strong Magnetic Fields
Autorzy:
Derzhko, O.
Krokhmalskii, T.
Richter, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813782.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.45.+j
75.50.Ee
Opis:
In the present paper we consider the low-temperature thermodynamic properties of the quantum Heisenberg antiferromagnet on the frustrated bilayer lattice in strong magnetic fields.Under certain conditions the isolated localized magnon states (singlets on vertical bonds;simultaneous occupation of neighboring vertical bonds is forbidden) are the ground states which dominate thermodynamics and induce a behavior inherent in the well known model of hard squares on a square lattice.We focus on magnetic properties discussing the magnetization and the susceptibility of the spin model.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 433-436
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Marshall-Peierls Sign Rule in Frustrated Heisenberg Chains
Autorzy:
Voigt, A.
Richter, J.
Powiązania:
https://bibliotekanauki.pl/articles/2013996.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.40.Mg
75.50.Ee
Opis:
We consider the frustrated antiferromagnetic s=1 Heisenberg quantum spin chain with regard to the Marshall-Peierls sign rule. Using exact diagonalization data we investigate the breakdown of the Marshall- Peierls sign rule in dependence on frustration and compare our findings with data for s=1/2. We calculate a critical value of frustration J$\text{}_{2}^{crit}$, where the Marshall-Peierls sign rule is violated. The extrapolation of this value to the infinite chain limit holds J$\text{}_{2}^{crit}$ ≈ 0.016, lower than in the case of s=1/2 (J$\text{}_{2}^{crit}$ ≈ 0.027). T his points to a stronger influence of frustration in the case of s=1. Nevertheless, the calculation of the weight of the Ising-states violating the Marshall- Peierls sign rule shows that the latter holds approximately even for a quite large frustration and may be used for numerical techniques.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 979-982
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Aspects of Superconducting Pairing
Autorzy:
Acquarone, M.
Paiusco, M.
Powiązania:
https://bibliotekanauki.pl/articles/1929387.pdf
Data publikacji:
1993-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.10.-z
75.10.Lp
75.50.Ee
Opis:
We discuss some of the recently proposed models dealing with the superconducting state in the presence of strong antiferromagnetic fluctuations, induced by the on-site Coulomb repulsion between electrons (the Hubbard correlation). In the weak coupling limit we treat the influence of correlation effects on the phonon-mediated superconductivity within the BCS-Eliashberg framework. As a non-standard model in this limit we describe next the so-called spin bag model. To discuss strong correlation limit, we describe first the projected Hamiltonian (the t-J Hamiltonian) and the corresponding antiferromagnetic state. The resonating valence bond model is introduced both as a naive version, equivalent to the BCS treatment of the transverse spin fluctuations, as well as a holon-spinon version.
Źródło:
Acta Physica Polonica A; 1993, 84, 1; 101-126
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Towards Spin-Wave Like Approach to the J-J Heisenberg Antiferromagnet in Terms of Composite Spins
Autorzy:
Grzybowski, P.
Chhajlany, R.
Powiązania:
https://bibliotekanauki.pl/articles/1810417.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.50.Ee
75.40.Cx
Opis:
Conventional spin-wave approach relies on an expansion around a relevant classical (unentangled) ground state or equivalently the ground state in the mean field approximation for the quantum model. However, for systems which may admit valence bond ground states, such as the staggered J-J' Heisenberg antiferromagnet, single site mean field approximation is obviously an incorrect zeroth order approximation. In this paper, we introduce a mean field approximation for clusters consisting of two spins connected by a strong bond in the aforementioned model. We identify the quantum critical point and calculate the ground state magnetization within this cluster mean field approximation in one and two dimensions. Finally, we derive an effective dimer Hamiltonian, in the standard basis operator formalism, which may be a basis for further spin-wave like expansions around the cluster mean field approximation ground state.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 168-170
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Spin-Low Spin Transitions in $Cu_{0.2}Co_{0.76}Cr_{1.83}Se_4$ Semiconductor
Autorzy:
Maciążek, E.
Groń, T.
Pacyna, A.
Mydlarz, T.
Krok-Kowalski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1489908.pdf
Data publikacji:
2012-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Wx
75.50.Dd
75.50.Ee
Opis:
Magnetization, ac and dc magnetic susceptibility measured in the zero-field-cooled mode were used to study the high spin-low spin transitions in polycrystalline $Cu_{0.2}Co_{0.76}Cr_{1.83}Se_4$ semiconductor. The real part component of fundamental susceptibility $χ_1^\prime$ (T) and its second $(χ_2)$ and third $(χ_3)$ harmonics revealed two spectacular peaks at 128 K and at 147 K, confirming the appearance of the spin-crossover phenomenon.
Źródło:
Acta Physica Polonica A; 2012, 121, 3; 687-689
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Characterization of Molecular Beam Epitaxy Grown $Cd_{1-x}$Mn$\text{}_{x}$Te Structures
Autorzy:
Sawicki, M.
Kolesnik, S.
Wojtowicz, T.
Karczewski, G.
Janik, E.
Kutrowski, M.
Żakrzewski, A.
Dynowska, E.
Dietl, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1931934.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
75.50.Rr
75.50.Ee
Opis:
The paper reports on the application of SQUID magnetometry to probe magnetic ion distribution in epilayers and at interfaces of diluted magnetic semiconductors. We present also new results on the possible influence of the magnetic confinement on the formation of the spin-glass phase, and on antiferromagnetic phase transition in zinc-blende MnTe.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 169-172
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic properties of the RbNd(WO₄)₂ single crystal
Autorzy:
Borowiec, M.
Zubov, E.
Zajarniuk, T.
Barański, M.
Powiązania:
https://bibliotekanauki.pl/articles/1075349.pdf
Data publikacji:
2016-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.50.Ee
75.10.-b
Opis:
The magnetic investigations as a function of the temperature and magnetic field for the rubidium neodymium double tungstate RbNd(WO₄)₂ single crystal have been performed. The magnetization was measured in the temperature range from 4.2 to 100 K and for the magnetic field up to 1.5 T. The crystal field and exchange parameters were found.
Źródło:
Acta Physica Polonica A; 2016, 129, 3; 359-361
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Effect of Spin-Density Wave Parameters on Shape of $\text{}^{119}$Sn Mössbauer Spectra
Autorzy:
Cieślak, J.
Dubiel, S. M.
Powiązania:
https://bibliotekanauki.pl/articles/1943948.pdf
Data publikacji:
1995-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.80.+y
75.30.Fv
75.50.Ee
Opis:
Based on a simple numerical procedure the influence of various parameters characteristic of spin-density waves on the shape of $\text{}^{119}$Sn Mössbauer spectra and the related histograms of the Hyperfine field distributions is investigated.
Źródło:
Acta Physica Polonica A; 1995, 88, 6; 1143-1150
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neutron Diffraction Studies of Tb_2Ni_{2-x}In Intermetallic Compounds
Autorzy:
Szytuła, A.
Baran, S.
Hoser, A.
Kalychak, Ya.M.
Penc, B.
Tyvanchuk, Yu.
Powiązania:
https://bibliotekanauki.pl/articles/1399026.pdf
Data publikacji:
2013-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.-j
75.47.Np
75.50.Ee
Opis:
The magnetic ordering of the $Tb_2Ni_{1.78}In$ and $Tb_2Ni_2In$ have been studied by neutron diffraction measurements. $Tb_2Ni_{1.78}In$ with the tetragonal $Mo_2FeB_2$-type (space group P4/mbm, tP10) is antiferromagnet with the Néel temperature equal to 20 K. Below this temperature Tb moments form collinear magnetic structure commensurate with the crystal, described by the propagation vectors equal to (1/4, 1/4, 1/2). Magnetic moment equal to 7.60(6) $μ_{B}$ is parallel to c-axis. The Tb_2Ni_2In in the orthorhombic $Mn_2$ $lB_2$-type (space group Cmmm, oC10) was detected as an impurity in the studied sample. It orders antiferromagnetically below ≈ 100 K with collinear moment arrangement described by the propagation vector (1/2, 1/2, 1/2). t 1.6 K $μ_{Tb}$ = 6.33(14) $μ_{B}$ and is parallel to the c-axis.
Źródło:
Acta Physica Polonica A; 2013, 124, 6; 994-997
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quadrupolar Magnetic Field Outside Antiferromagnetic Cr$\text{}_{2}$O$\text{}_{3}$
Autorzy:
Borovik-Romanov, A. S.
Nizhankovskii, V. I.
Powiązania:
https://bibliotekanauki.pl/articles/1964685.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.-b
75.25.+z
75.50.Ee
Opis:
Predicted by Dzyaloshinskii quadrupolar magnetic field outside antiferromagnet was experimentally observed for Cr$\text{}_{2}$O$\text{}_{3}$ single crystal. The magnetic quadrupole sharply disappeared with heating the sample above T$\text{}_{N}$=317 K and appeared again on cooling below T$\text{}_{N}$. The obtained value of the magnetic quadrupole is in reasonable agreement with theoretical estimation.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 371-374
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Ordering of RAgSb$\text{}_{2}$ Compounds
Autorzy:
André, G.
Bourée, F.
Kolenda, M.
Leśniewska, B.
Oleś, A.
Szytuła, A.
Powiązania:
https://bibliotekanauki.pl/articles/2013392.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.30.Kz
75.50.Ee
Opis:
The magnetic structures of the polycrystalline samples of RAgSb$\text{}_{2}$ (R=Ce, Pr, Nd, Tb-Tm) are determined. All compounds crystallize in the tetragonal ZrCuSi$\text{}_{2}$-type of crystal structure and except CeAgSb$\text{}_{2}$ they are antiferromagnets with a Néel temperature of 11 K for R = Tb and 2 K for Tm. CeAgSb$\text{}_{2}$ below T$\text{}_{C}$=9.5 K is ferromagnet with the magnetic moment equal to 0.33μ$\text{}_{B}$ and parallel to c-axis. In NdAgSb$\text{}_{2}$ the sine modulated magnetic ordering described by the wave vector k = (0.5435,0,0) is observed. Below T$\text{}_{N}$ a collinear antiferromagnetic structure with the magnetic (a,a,2c) for R = Pr and (2a,a,c) for R = Tb, Dy, Ho, and Er is observed. For Ho-compound with an increase in temperature the coexistence of two structures is observed: commensurate collinear and incommensurate sine modulated. In TmAgSb$\text{}_{2}$ the coexistence of the two phases is observed at T = 1.4 K. With an increase in temperature only the incommensurate phase stays.zapisz i
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 771-774
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Soft-Mode vs. Localized Moments Regimes of Spin Fluctuations in Itinerant Electron Magnetism
Autorzy:
Solontsov, A.
Lacroix, C.
Wagner, D.
Powiązania:
https://bibliotekanauki.pl/articles/1964668.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Gb
75.10.Lp
75.50.Ee
Opis:
An analysis of different regimes of spin fluctuation behaviour in anharmonic itinerant electron magnets is presented basing on the recently worked out soft-mode theory of spin fluctuations.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 359-362
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Large Magnetocaloric Effect in $Nd_{2}Ni_{2}In$
Autorzy:
Maskova, S.
Danis, S.
Llobet, A.
Nakotte, H.
Havela, L.
Powiązania:
https://bibliotekanauki.pl/articles/1368761.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Kz
75.30.Sg
Opis:
$Nd_{2}Ni_{2}In$ is an antiferromagnet ($T_{N}$=8 K) with crystal structure equivalent to the Shastry-Sutherland lattice, possibly leading to the magnetic frustration. The AF coupling with moments in the basal plane can be driven by weak magnetic fields (<0.2 T) into the c-axis ferromagnet. The situation leads to large changes of magnetic entropy in fields below 1 T, which makes $Nd_{2}Ni_{2}In$ a candidate for magnetocaloric applications. The entropy change is 9.6 J/(kg K) in fields of 1 T.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 282-283
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Temperature Physical Properties of Single-Crystalline EuCoGe₃ and EuRhGe₃
Autorzy:
Bednarchuk, O.
Kaczorowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/1386301.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
72.15.-v
65.40.-b
Opis:
Since a few years europium-based intermetallics have been attracting more and more attention due to their intriguing physical properties with anomalous behaviours in magnetically ordered states. Here, we report on the formation and the bulk physical properties of two tetragonal compounds EuCoGe₃ and EuRhGe₃, studied on high-quality single-crystalline specimens. In both materials, the Eu ions are in their divalent state, which gives rise to an antiferromagnetic ordering below $T_{N}$ = 15.4 K and $T_{N}$ = 11.3 K, respectively. In addition, EuCoGe₃ exhibits a successive antiferromagnetic phase transition at T₂ = 13.4 K. Based on some characteristic features in the temperature variations of the magnetic susceptibility, specific heat and electrical resistivity, we suggest that in both germanides an amplitude modulated magnetic structure develops below the respective $T_{N}$, with the Eu magnetic moments directed along the crystallographic [001] axis in EuCoGe₃ and perpendicular to this direction in EuRhGe₃.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 418-420
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Ground-State of the Quantum Spin-1/2 Heisenberg Antiferromagnet on Square-Kagomé Lattice: Resonating Valence Bond Description
Autorzy:
Tomczak, P.
Molińska, A.
Richter, J.
Schulenburg, J
Powiązania:
https://bibliotekanauki.pl/articles/2046847.pdf
Data publikacji:
2006-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.45.+j
75.50.Ee
Opis:
In this paper we report on some ground-state properties of the spin-1/2 Heisenberg antiferromagnet on the two-dimensional square-kagomé lattice. Finite N-spin systems were investigated with the use of the resonating valence bond method. Like in the case of spin system on kagomé lattice we find the almost flat dependence of mean singlet length on 1/N.
Źródło:
Acta Physica Polonica A; 2006, 109, 6; 781-787
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Details of Magnetic Properties in $Pb(Fe_{1/2}Nb_{1/2})O_{3}$
Autorzy:
Maryško, M.
Laguta, V.
Raevski, I.
Powiązania:
https://bibliotekanauki.pl/articles/1372364.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.85.+t
75.50.Ee
Opis:
For $Pb(Fe_{0.5}Nb_{0.5})O_{3}$ the χ(T) and m(H) measurements up to 70 kOe were performed with the aim to estimate the antiferromagnetic (AFM) and superantiferromagnetic (SAF) contribution to χ(T). Below $T_{N}$ the increase of χ(T) is attributed to a small part of $Fe^{3+}$ ions in the SAF clusters. For high fields the suppression of the AFM and enhancement of the SAF susceptibility was observed. An inflection point of the m(H) curves below the Néel point suggests the presence of a spin reorientation process connected with the AFM phase.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 376-377
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisotropic Magnetic Properties of URhIn₅ Compound
Autorzy:
Bartha, A.
Kratochvílová, M.
Sechovský, V.
Custers, J.
Dušek, M.
Powiązania:
https://bibliotekanauki.pl/articles/1385560.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.50.Ee
81.10.Dn
Opis:
We report on synthesis and anisotropic physical properties of URhIn₅. High quality single crystals were grown from In self-flux. The compound undergoes a second-order phase transition into an antiferromagnetic state at $T_{N}$ = 98 K. The transition is magnetic field independent up to 9 T. An increase of the resistivity ρ with j along the [100], [110] and [001] tetragonal axis indicates a spin-density-wave induced order with the gap opening first along the [001] direction. The magnetic susceptibility χ = M/H exhibits a strong anisotropy. Above T= 200 K, χ(T) follows the Curie-Weiss law with the effective moment of $μ_{eff}$ = 3.71 $μ_{B}$/U and the Weiss temperatures of $θ_{P}^{[100]}$ = -900 K and $θ_{P}^{[001]}$ = -500 K for H ∥ [100] and H ∥ [001], respectively. The characteristic Kondo-like temperature for URhIn₅ yields $T_{K}$= 125 K.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 339-341
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ab initio Calculation of Quasi-Equilibrium Microcracks in Cubic Boron Nitride
Autorzy:
Góra, D.
Parlinski, K.
Powiązania:
https://bibliotekanauki.pl/articles/2035553.pdf
Data publikacji:
2002-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.Mb
75.50.Ee
62.20.Mk
Opis:
A crack in cubic boron nitride crystal was simulated within the ab initio density-functional theory. The lattice constant, critical stress intensity factor K$\text{}_{c}$, which describes crack creation stress, and fracture surface energy Γ were calculated from the elongated 2×6×1 supercell and these quantities agree quite well with the experimental data. We conclude that density-functional theory can be used to estimate crack's material constants.
Źródło:
Acta Physica Polonica A; 2002, 102, 3; 437-442
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Study of Phases in FeVO₄-Co₃V₂O₈ System
Autorzy:
Guskos, N.
Zolnierkiewicz, G.
Pilarska, M.
Typek, J.
Blonska-Tabero, A.
Aidinis, C.
Powiązania:
https://bibliotekanauki.pl/articles/1030217.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.50.Ee
76.30.Fc
Opis:
Magnetic properties of four nFeVO₄/(1-n)Co₃V₂O₈ samples obtained in reactions between FeVO₄ and Co₃V₂O₈ (n = 0.96, 0.86, 0.84 and 0.83, samples designated S1, S3, S4, S5, respectively) have been investigated by DC magnetisation in field cooling and zero-field-cooling modes and EPR. DC magnetic susceptibility showed paramagnetic behavior of all samples in high-temperature range (T > 20 K) and transition to antiferromagnetic state at 16-18 K (depending on sample iron content). Additional magnetic freezing at 8 K was registered for S3-S5 samples containing larger amount of cobalt. The Curie-Weiss law in 100-300 K temperature range indicates that Co²⁺ is in the high-spin state (S = 3/2). From the parameters of the hysteresis loop observed for the samples it was calculated that 0.58% of all magnetic (Fe³⁺, Co²⁺) ions were involved in the ferromagnetic states. EPR spectra of the samples were recorded in high temperature range (T > 90 K). The temperature dependence of the spectral parameters (resonance field, linewidth, integrated intensity) suggested the Fe³⁺ high-spin ions coupled by antiferromagnetic interaction and clusters of ions play major role in EPR spectra.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 24-30
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Complex Magnetic Behaviour of $Ho_3Cu_4X_4$ Compounds (X = Si and Sn)
Autorzy:
Gondek, Ł.
Szytuła, A.
Prokhnenko, O.
Powiązania:
https://bibliotekanauki.pl/articles/1813174.pdf
Data publikacji:
2008-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.+z
75.50.Ee
75.40.Cx
Opis:
Ternary $Ho_3Cu_4X_4$ compounds exhibit very complex magnetic phase diagrams. The rare earth ions occupy two non-equivalent crystal positions. Within both magnetic sublattices, magnetic moments exhibit different magnetic ordering temperatures. Moreover, in light of our results, it seems that both sublattices are weakly coupled between each other. This may be observed as independent changes of propagation vectors etc. The major difference of ordering temperatures between both compounds is likely related to substantial change of interatomic distances. Consequently, completely different crystalline electric field effects are observed.
Źródło:
Acta Physica Polonica A; 2008, 113, 4; 1179-1184
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of RRhGe (R = Dy and Tm) Compounds
Autorzy:
Bażela, W.
Hofmann, M.
Baran, S.
Penc, B.
Szytuła, A.
Zygmunt, A.
Powiązania:
https://bibliotekanauki.pl/articles/2013666.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.30.Kz
75.50.Ee
Opis:
The magnetic properties of the ternary intermetallic RRhGe (R = Dy and Tm) were investigated by magnetic and neutron diffraction measurements. These compounds crystallize in a TiNiSi-type orthorhombic structure and are antiferromagnets with the Néel temperature 20 K (R = Dy) and 6.2 K (R = Tm). The neutron diffraction data reveal that the magnetic order in TmRhGe is collinear with the magnetic unit doubled along the b-axis respective to the crystal one.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 819-822
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Co Doping on Crystal and Magnetic Properties of $Gd_2Cu_2In$
Autorzy:
Gondek, Ł.
Szytuła, A.
Kaczorowski, D.
Szewczyk, A.
Gutowska, M.
Tyvanchuk, Yu.
Kalychak, Ya.
Powiązania:
https://bibliotekanauki.pl/articles/1419907.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
75.30.Kz
75.50.Ee
Opis:
Physical properties of $Gd_2Cu_{2 - x}Co_{x}In$ (x = 0.1, 0.2, 0.3) samples are investigated. The paper brings results of X-ray diffraction, magnetometric as well as specific heat studies. It was found that only sample with x = 0.1 exhibits desired crystal structure. Other compositions show existence of impurities due to lack of dissolution Co atoms. For $Gd_2Cu_{1.9}Co_{0.1}In$ sample the Curie temperature of 92.5 K was evidenced. Thus, an enhancement of ferromagnetic correlations with comparison to $Gd_2Cu_2In$ sample was evidenced. It was found that $Gd_2Cu_{1.9}Co_{0.1}In$ sample exhibits magnetocaloric effect within broad temperature range.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 216-219
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Wave Dynamics of 2D and 3D Heisenberg Antiferromagnets
Autorzy:
Cowley, R.
Tennant, D.
Coldea, R.
Powiązania:
https://bibliotekanauki.pl/articles/1810280.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Gb
75.50.Ee
61.12.Ex
Opis:
The excitations of the 2D Heisenberg antiferromagnet, $Rb_2MnF_4$, were studied using neutron scattering techniques with the MAPS spectrometer at the ISIS facility of Rutherford Appleton Laboratory. Measurements were made of the magnetic excitations over the whole 2D Brillouin zone at 6 temperatures below the ordering temperature of 38 K and 6 temperatures above. It was found that the excitations were well defined if their wave vectors were larger than the inverse correlation length and were overdamped if the wave vectors of the excitations were smaller than the inverse correlation length. In more detail we have compared our experimental results with the results of classical simulations and the results gave a very adequate description of the experimental results except at the lowest temperature where the form of the dispersion relation was correct but the energies of the excitations were in error. Nevertheless, classical simulations do provide an efficient and easily implemented methodology for modelling the excitations in the Heisenberg magnets. The damping of the excitations was experimentally found to follow a $T^2$ behaviour over all wave vector and energy scales. This is in agreement with the classical simulations but inconsistent with analytic theories of the damping for the 2D Heisenberg model and in particular does not agree with hydrodynamic behaviour or dynamic scaling. The result is similar to that found in 3D Heisenberg systems and suggests that more analytic theory is needed to explain the experimental results for both 2D and 3D Heisenberg magnets.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 19-24
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Correlation Theory of Antiferromagnet Cr$\text{}_{2}$O$\text{}_{3}$ for T>T$\text{}_{N}$
Autorzy:
Latacz, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1964710.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Gb
75.50.Ee
25.40.Fq
Opis:
A correlation theory is applied to two-sublattice antiferromagnet Cr$\text{}_{2}$O$\text{}_{3}$, for T>T$\text{}_{N}$. This theory includes pair correlation effects in a self-consistent calculation of both static and dynamic properties. The two kinds of approximations are assumed: the two-pole approximation for the relaxation function of the random force and the mode-mode decoupling procedure for the static and dynamic higher-order quantities. The formulae for the static susceptibility, line-shape function and magnetic cross-section of the inelastic neutron scattering are given for the case of a non-Bravais two-sublattice antiferromagnet.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 403-405
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Neutron Irradiation on the EPR Spectra of CuGeO$\text{}_{3}$
Autorzy:
Mosiniewicz-Szablewska, E.
Gładczuk, L.
Dąbkowska, H. A.
Pytel, B.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/2013725.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.50.Ee
76.30.Da
Opis:
The influence of neutron irradiation on the electron paramagnetic resonance spectra of the spin-Peierls compound CuGeO$\text{}_{3}$ was investigated in the wide temperature range 2-300 K. It was found that the irradiation induced appreciable changes in the EPR signal intensity, resonance line width and g-factor of this material. It was also shown that the irradiation leads to a decrease in the spin-Peierls transition temperature. For higher irradiation doses, an antiferromagnetically ordered phase can be observed at lower temperatures. This phase coexists with the spin-Peierls phase. The observed decrease in the spin-Peierls transition temperature after irradiation may be associated with some changes in topological and chemical short-range order or with the transmutation of the fraction of $\text{}^{63}$Cu in the $\text{}^{63}$Cu(n,α)$\text{}^{60}$Co reaction.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 897-900
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Crossover in Cu$\text{}_{x}$Co$\text{}_{y}$Cr$\text{}_{z}$Se$\text{}_{4}$ Semiconductors
Autorzy:
Maciążek, E.
Groń, T.
Pacyna, A. W.
Mydlarz, T.
Zawisza, B.
Krok-Kowalski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2048134.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Wx
75.50.Dd
75.50.Ee
Opis:
Magnetization and magnetic susceptibility measured in the zero-field-cooled mode were used to study the spin crossover transition in polycrystalline Cu$\text{}_{x}$Co$\text{}_{y}$Cr$\text{}_{z}$Se$\text{}_{4}$ compounds. With increasing Co content a transition from ferromagnetic order via ferrimagnetic one to antiferromagnetic-like behaviour was observed. This transition is accompanied with a lowering symmetry from cubic to monoclinic and for the latter the spin crossover phenomenon occurs. These results are considered in a framework of the ligand-field split and the spin-orbit coupling.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 711-713
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Glass State in S=3/2 Kagomé Antiferromagnet $Co(N_{3})_{2}(bpg)[(CH_{3})_{2}(NCOH)]_{4/3}$
Autorzy:
Vrábel, P.
Čižmár, E.
Orendáčová, A.
Gao, S.
Orendáč, M.
Powiązania:
https://bibliotekanauki.pl/articles/1368680.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Et
75.10.Nr
Opis:
Specific heat, magnetic susceptibility and magnetization of $Co(N_{3})_{2}(bpg)[(CH_{3})_{2}(NCOH)]_{4/3}$, representing S=3/2 kagomé system are reported. Long-range ordering at 16 K was revealed, however, at lower temperatures slow spin dynamics is still found. The analysis of alternating susceptibility suggests the onset of glassy state. The study of the time dependence of magnetization revealed the existence of more relaxation channels with pronounced different relaxation times. The observed behaviour is consistent with the formation of topological spin glass in which relaxation is governed by both spin and chiral degrees of freedom.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 266-267
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neutron Diffraction Studies of Nanoparticle $DyMnO_3$ Compound
Autorzy:
Szytuła, A.
Penc, B.
Dyakonov, V.
Baran, S.
Hoser, A.
Powiązania:
https://bibliotekanauki.pl/articles/1206328.pdf
Data publikacji:
2014-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.F-
75.25.-j
75.50.Ee
Opis:
The neutron powder diffraction (NPD) measurements of the nano-size $DyMnO_3$ manganite have been performed. The obtained results indicate that this compound crystallizes in the orthorhombic crystal structure described by the space group Pnma. The Mn and Dy moments order antiferromagnetically at different temperatures and form modulated magnetic structure described by the propagation vector k=($k_x$, 0, 0) with the different values of $k_x$ component for the Mn and Dy sublattices. The values of $k_x$ component for Mn sublattice increase with decreasing of the temperature and are smaller that in bulk compound. The wide Bragg peaks related to the Dy sublattice suggest that the magnetic order in this sublattice has the cluster-like character.
Źródło:
Acta Physica Polonica A; 2014, 125, 1; 65-66
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of NpPdSn
Autorzy:
Gofryk, K.
Griveau, J.
Jardin, R.
Colineau, E.
Rebizant, J.
Wastin, F.
Caciuffo, R.
Powiązania:
https://bibliotekanauki.pl/articles/1810298.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
71.27.+a
75.30.Mb
Opis:
A new compound NpPdSn was prepared and studied by X-ray diffraction, magnetization, heat capacity and electrical resistivity measurements, performed in the temperature range 2-300 K and under magnetic field up to 14 T. The crystal structure determined by single-crystal X-ray analysis is hexagonal with ZrNiAl-type (space group $P\bar{6}2m$). NpPdSn orders antiferromagnetically at 19 K and exhibits a Curie-Weiss behavior with $μ_\text{eff}=2.66 μ_{B}$ and $Θp_{p}$=-47 K. Bulk properties show temperature variations similar to systems with strong electronic correlations with a large negative paramagnetic Curie temperature and an enhanced low-temperature specific heat (γ≈90 mJ/(mol $K^{2}$)). It suggests that NpPdSn may be classified as a new Np-based antiferromagnetic Kondo lattice, one of the very few known amidst transuranium-based intermetallics.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 80-82
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New S=1/2 Alternating Chain Compound - High Pressure Form of (VO)$\text{}_{2}$P$\text{}_{2}$O$\text{}_{7^{-}}$
Autorzy:
Azuma, M.
Saito, T.
Hiroi, Z.
Takano, M.
Narumi, Y.
Kindo, K.
Powiązania:
https://bibliotekanauki.pl/articles/2012882.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.40.Cx
75.50.Ee
Opis:
The high-pressure phase of (VO)$\text{}_{2}$P$\text{}_{2}$O$\text{}_{7}$ comprises a unique kind of spin-1/2 Heisenberg alternating antiferromagnetic chain, in contrast with the ambient pressure phase containing two crystallographically different chains. Magnetic susceptibility and high-field magnetization data showed the presence of a single spin gap of 23 (magnetization) ~27 (susceptibility) K, not double as observed for the ambient pressure phase. This result shows that the two kinds of chains of the ambient pressure phase have single, different spin gaps.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 205-208
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pairing-Symmetry Selection in a Weakly Doped Canted Antiferromagnet on the Triangular Lattice
Autorzy:
Wróbel, P.
Suleja, W.
Powiązania:
https://bibliotekanauki.pl/articles/1812329.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
74.20.Mn
75.50.Ee
Opis:
The mechanism of superconductivity generation by spin fluctuations in the electron doped canted antiferromagnet on the triangular lattice was analyzed. The underlying assumption is that the formation of the bound state is the prerequisite of pairing. The outcome of this analysis is also valid if an additional isotropic attraction is active but the anisotropic spin-fluctuation mediated force decides on the symmetry of the two-particle bound state. When the canted antiferromagnetic state is generated, the symmetry of the point group $C_{6v}$ for the triangular lattice is lowered to the symmetry of $C_{3v}$. It is demonstrated that spin fluctuations definitely favor the p-wave bound state, which transforms according to the E representation of $C_{3v}$. Since the inversion is not an element of $C_{3v}$, the parity is not a good quantum number and thus the predicted paired state will be a mixture of singlet and triplet. Such a scenario may be relevant to physics of superconducting triangular cobaltates or organics.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 225-228
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spontaneous Surface Magnetisation of Single Crystal MnF$\text{}_{2}$ in the Antiferromagnetic State
Autorzy:
Nizhankovskii, V. I.
Khar'kovskii, A. I.
Zaleski, A. J.
Powiązania:
https://bibliotekanauki.pl/articles/2013077.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Pd
75.25.+z
75.50.Ee
Opis:
Spontaneous magnetisation of (100) and (010) surfaces of a MnF$\text{}_{2}$ single crystal in the antiferromagnetic state is discovered. A sign of the surface magnetisation is determined by a difference in dielectric constants ε of MnF$\text{}_{2}$ and ambient matter: magnetisation is directed to the substance with a smaller ε.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 487-490
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of the $Mn_5Si_3$ Compound
Autorzy:
Leciejewicz, J.
Penc, B.
Szytuła, A.
Jezierski, A.
Zygmunt, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813176.pdf
Data publikacji:
2008-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Lp
75.25.+z
75.50.Ee
Opis:
The magnetic and powder neutron diffraction data indicate a complex magnetic structure of $Mn_5Si_3$. This compound has the hexagonal D8_8 crystal structure at room temperature. The Mn atoms occupy two nonequivalent sublattices. Two phase transitions, at 60 and 106 K, are observed. The first one is between a non-collinear AF1 and a collinear AF2 magnetic structure, the second one is between the collinear AF2 structure and a paramagnetic state. At 106 K the crystal structure changes from the hexagonal to the orthorhombic one. The values of the Mn magnetic moment in both structures were calculated by different ab initio methods. The results of the calculations are compared with the values of the Mn magnetic moment determined experimentally in this work and presented in the previous ones.
Źródło:
Acta Physica Polonica A; 2008, 113, 4; 1193-1203
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of RCuGe (R=Pr, Nd, Gd, Tb, Dy, Ho, Er) Compounds
Autorzy:
Baran, S.
Leciejewicz, J.
Stüsser, N.
Szytuła, A.
Tomkowicz, Z.
Zygmunt, A.
Powiązania:
https://bibliotekanauki.pl/articles/1964562.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.30.Kz
75.50.Ee
Opis:
The magnetic properties including the magnetic structure were determined by magnetometric and neutron diffraction measurements of the polycrystalline samples. RCuGe compounds are antiferromagnets at low temperatures, with T$\text{}_{N}$ ranging from 2.2 K for R = Pr to 17 K for R = Gd. The external magnetic field causes a change in the type of the magnetic ordering from antiferro- to ferromagnetic state. From the neutron diffraction data the magnetic structure of all RCuGe compounds are determined. In the case of ErCuGe below T$\text{}_{N}$ an additional phase transition is observed. The obtained experimental data are discussed in terms of an exchange interaction of the RKKY-type and crystalline electric field.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 271-275
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermodynamic Properties of Geometrically Frustrated S=1/2 XY Antiferromagnet $Er_{2}Sn_{2}O_{7}$
Autorzy:
Al Ghamdi, N.
Orendáčová, A.
Pavlík, V.
Orendáč, M.
Powiązania:
https://bibliotekanauki.pl/articles/1368676.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Dg
75.50.Ee
75.30.Sg
Opis:
The magnetic susceptibility, specific heat and entropy of geometrically frustrated S=1/2 XY antiferromagnet $Er_{2}Sn_{2}O_{7}$ are reported. It is shown, that temperature dependence of magnetic susceptibility above nominally 10 K is governed by crystal field effects. Systematic study of specific heat in magnetic fields up to 7 T enabled the estimation of exchange coupling, J/k<<4.6 K. Investigation of isothermal change of magnetic entropy upon magnetization from 1 T to 7 T revealed the absence of enhanced magnetocaloric effect. The obtained results suggest that frustration parameter f ≈140 proposed for $Er_{2}Sn_{2}O_{7}$ earlier may be significantly overestimated.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 264-265
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Competing Magnetic Interactions in Zn$\text{}_{3}$Fe$\text{}_{4}$V$\text{}_{6}$O$\text{}_{24}$ Studied by Electron Paramagnetic Resonance
Autorzy:
Zolnierkiewicz, G.
Guskos, N.
Typek, J.
Blonska-Tabero, A.
Powiązania:
https://bibliotekanauki.pl/articles/2046813.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
75.50.Dd
75.50.Ee
Opis:
A multicomponent vanadate M$\text{}_{3}$Fe$\text{}_{4}$V$\text{}_{6}$O$\text{}_{24}$ sample with non-magnetic M = Zn(II) ions was synthesized by the solid state reaction method using stoichiometric mixtures of the 80mol% FeVO$\text{}_{4}$ and 20mol% Zn$\text{}_{3}$(VO$\text{}_{4}$)$\text{}_{2}$. The temperature dependence of the EPR spectra was performed in the 90-280 K temperature range. The resonance field and the integrated intensity of the EPR line showed minimum value of both parameters at≈200 K. It is suggested that a part of the sample is displaying tendency to form an antiferromagnetic ordered state (or the magnetic clusters) above this temperature while below the ferromagnetic interaction of the main part of material is dominating. This behaviour is attributed to the inherent magnetic inhomogeneity of the system due to the presence of the ferromagnetic or antiferromagnetic spin clusters.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 675-679
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of $TbNi_{1-x}Au_{x}In$ Compounds
Autorzy:
Bałanda, M.
Penc, B.
Baran, S.
Jaworska-Gołąb, T.
Arulraj, A.
Szytuła, A.
Powiązania:
https://bibliotekanauki.pl/articles/1810419.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Lp
75.25.+z
75.50.Ee
Opis:
Polycrystalline samples of $TbNi_{1-x}Au_{x}In$ for x = 0.1, 0.2, 0.4, 0.6 and 0.8 were prepared and studied by powder X-ray and neutron diffraction and ac magnetic susceptibility measurements. These compounds crystallize in the hexagonal ZrNiAl-type structure. With increasing Au content a change in the magnetic structure is observed. For x = 0.1, 0.2 and 0.4 the magnetic order is described by the propagation vector k = (1/2, 0, 1/2) while for x = 0.8 by k = (0, 0, 1/2). Between 1.5 K and the Néel temperature the magnetic order is stable.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 174-177
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Quadrupole Interaction on $\text{}^{57}$Fe Mössbauer Spectra for Samples with Charge- and Spin-Density Waves
Autorzy:
Cieślak, J.
Dubiel, S. M.
Powiązania:
https://bibliotekanauki.pl/articles/1964225.pdf
Data publikacji:
1997-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.80.+y
75.30.Fv
75.50.Ee
Opis:
The influence of the quadrupole interaction on the shape of $\text{}^{57}$Fe Mössbauer spectra expected for samples with charge-density waves andor spindensity waves is investigated. It is shown, by model calculations, that both for the commensurate and for incommensurate charge-density waves andor spin-density waves the shape of $\text{}^{57}$Fe Mössbauer spectra is sensitive to the value, and for asymmetric spectra, to the sign of quadrupole interaction. This necessitates an inclusion of quadrupole interaction when analyzing the spectra recorded on samples exhibiting charge-density waves andor spin-density waves, and having a symmetry lower than cubic.
Źródło:
Acta Physica Polonica A; 1997, 91, 6; 1131-1139
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Heavy Ion Irradiation on the Magnetic Properties of CuGeO$\text{}_{3}$
Autorzy:
Gładczuk, L.
Mosiniewicz-Szablewska, E.
Szymczak, R.
Baran, M.
Dąbkowska, H. A.
Choiński, J.
Czosnyka, T.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/2013715.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.50.Ee
76.30.Da
Opis:
The influence of heavy ion irradiation on the magnetic properties of the spin-Peierls compound CuGeO$\text{}_{3}$ has been investigated by means of the electron paramagnetic resonance, the spontaneous magnetization, and the low field ac susceptibility. The measurements were performed on the CuGeO$\text{}_{3}$ single crystals before and after irradiation with 80 MeV oxygen ions in the wide temperature range of 2-300 K. It was found that the irradiation induced an increase in the EPR signal intensity, magnetization, and susceptibility of this material. It was also shown that the irradiation does not lead to a decrease in the spin-Peierls transition temperature and to the formation of an antiferromagnetic phase which is expected to appear in disordered spin-Peierls systems.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 871-874
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$CuBr_2(C_{10}H_8N_2) - S = 1//2$ Two-Dimensional Rectangular Heisenberg Antiferromagnet
Autorzy:
Čižmár, E.
Kajňaková, M.
Orendáčová, A.
Orendáč, M.
Feher, A.
Anders, A.
Park, J.
Meisel, M.
Powiązania:
https://bibliotekanauki.pl/articles/1534990.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Et
75.50.Ee
76.30.-v
Opis:
Magnetic susceptibility and X-band electron spin resonance study of a two-dimensional Heisenberg antiferromagnetic system $CuBr_2$(bipy), where bipy = $C_{10}H_8N_2$ is 4,4'-bipyridyl, has been performed in the temperature range from 300 K down to 2 K. A rhombic anisotropy of the g-factor was obtained from X-band EPR measurements with $g_{x}$ = 2.037, $g_{y}$ = 2.100 and $g_{z}$ = 2.219. The temperature dependence of the magnetic susceptibility with a round maximum observed at 28 K suggests antiferromagnetic type of short-range order. No signature of the magnetic long-range order in studied compound was observed. The comparison of the magnetic susceptibility data with a two-dimensional rectangular Heisenberg model yields the values of intralayer exchange couplings J/$k_{B}$ = - 47 K and J'/$k_{B}$ = - 9.4 K.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 973-974
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Crystal and Magnetic Structure of BiFeO$\text{}_{3}$ Using Neutron Diffraction
Autorzy:
Sosnowska, I.
Przeniosło, R.
Fischer, P.
Murashov, V. A.
Powiązania:
https://bibliotekanauki.pl/articles/1931685.pdf
Data publikacji:
1994-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.84.Bw
61.12.Gz
75.50.Ee
Opis:
Polycrystalline material obtained from the ground single crystal of BiFeO$\text{}_{3}$ reported as not having the superstructure, shows the superstructure reflections in neutron diffraction pattern. The determined magnetic moment of antiferromagnetically ordered Fe$\text{}^{3+}$ ions is μ$\text{}_{Fe}$ = (3.70±0.03)μ$\text{}_{B}$ at 293 K.
Źródło:
Acta Physica Polonica A; 1994, 86, 4; 629-631
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermoelectric Power of the $URu_{1-x}Pd_{x}Ge$ System
Autorzy:
Gralak, D.
Toliński, T.
Tran, V.
Powiązania:
https://bibliotekanauki.pl/articles/1385279.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
75.50.Ee
72.15.Jf
Opis:
We report the measurements of thermoelectric power, S(T), of the $URu_{1-x}Pd_{x}Ge$ solid solutions in the temperature range 1.9-300 K. It is found that S(T) of URuGe is consistent with the behaviour of Kondo lattice, characterized by a low-temperature negative minimum and a high-temperature positive maximum. On the contrary, S(T) of the compositions 0.1 ≤ x ≤ 0.7 is negative over the whole temperature range measured and shows only one negative minimum around 200 K. The compositions x = 0.9 and 1, in addition to a high-temperature negative minimum, exhibit anomalies at low temperatures, presumably associated with the magnon drag. We interpret the experimental data assuming the presence of the Kondo and crystal-electric field effects.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 287-289
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermoelectric Power of Single-Crystalline $Ce_{2}RhSi_{3}$
Autorzy:
Szlawska, M.
Kaczorowski, D.
Plackowski, T.
Gulay, L.
Powiązania:
https://bibliotekanauki.pl/articles/1810404.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
75.50.Ee
72.15.Jf
Opis:
High-quality single crystal of $Ce_{2}RhSi_{3}$ was studied by means of thermoelectric power measurements carried out down to 2 K in external magnetic fields up to 13 T. The results obtained above 50 K were interpreted in terms of a modified two-band model that takes into account temperature variation of the width of 4f-derived narrow band located near the Fermi level. At lower temperatures the thermopower exhibits more complex temperature dependences that likely involve interplays of magnetic exchange, Kondo and crystal-field interactions.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 132-134
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Specific Heat and Magnetic Structure of GdT$\text{}_{2}$X$\text{}_{2}$ Compounds (T = Cu, Ni, X = Sn, Sb)
Autorzy:
Kaczmarska, K.
Pierre, J.
Schmitt, D.
Lambert-Andron, B.
Belllisent, R.
Guzik, A.
Powiązania:
https://bibliotekanauki.pl/articles/1964649.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.+z
75.40.-s
75.50.Ee
Opis:
The magnetic specific heat of GdNi$\text{}_{2}$Sn$\text{}_{2}$, GdNi$\text{}_{2}$Sb$\text{}_{2}$ and GdCu$\text{}_{2}$Sb$\text{}_{2}$ shows a λ-type anomaly at T$\text{}_{N}$ with a noticeable reduction of the discontinuity compared to that expected for a simple antiferromagnet. It can be associated with the existence of amplitude modulated magnetic structure just below T$\text{}_{N}$. Above T$\text{}_{N}$ a weak magnetic contribution is observed, evidencing the short-range ordering. From neutron diffraction studies it can be also concluded that investigated compounds have not simple antiferromagnetic structures. For GdNi$\text{}_{2}$Sn$\text{}_{2}$ the propagation vector Q=(0.3,1/2,1/2) was found with the magnetic moments along the [1,0,0] axis.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 347-350
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic and Electronic Properties in Series of $GdT_{x}Ga_{4-x}$ Solid Solutions (T = Ni or Cu)
Autorzy:
Wiśniewski, P.
Gorzelniak, R.
Kaczorowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/1385707.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
72.15.-v
72.15.Jf
Opis:
We present results of extensive measurements of magnetic susceptibility, electrical resistance, specific heat and thermoelectric power of two series of solid solutions $GdNi_{x}Ga_{4-x}$ and $GdCu_{x}Ga_{4-x}$, for ranges of doping x from 0.6 to 1 and from 1 to 1.5, respectively. All studied phases display the Curie-Weiss behaviour of magnetic susceptibility and antiferromagnetic ordering at temperatures below 23 K. Substitution of gallium with transition metal atoms has strong influence on Néel temperatures of all studied phases, shifting them by few K, depending on x. Metamagnetic-like anomalies are observed for some compositions. Behaviour of the electrical resistivity reveals metallic nature of all samples. Their magnetic ordering is reflected in low-temperature anomalies of the resistivity and the heat capacity.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 382-384
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Specific Heat and Magnetic Properties of Single-Crystalline $(Zn_{0.925}In_{0.054})[Cr_{1.84}In_{0.152}]Se_4$ Semiconductor
Autorzy:
Malicka, E.
Groń, T.
Pacyna, A.
Ślebarski, A.
Goraus, J.
Gągor, A.
Mydlarz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1409656.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.Ba
75.50.Ee
75.50.Pp
Opis:
An antiferromagnetic order with a Néel temperature $T_{N}$ = 17.5 K, a strong ferromagnetic exchange evidenced by a positive Curie-Weiss temperature $\Theta_{CW}$ = 77.3 K, the fuzzy peaks in the real component of susceptibility χ'(T) and the disappearance of the second critical field were established. The curvature of specific heat C(T) and C(T)/T in surrounding of $T_{N}$ indicated a broad peak, characteristic for the system with inhomogeneous magnetic state (spin-glass-like phase). The calculated magnetic entropy showed the value of S(T) ≈ 1 J/(mol K) which is extremely small; i.e., much lower than the magnetic contribution Rln(2S + 1) = 11.52 J/(mol K) calculated for the spin 3/2.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1108-1110
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonfrustrated Antiferromagnet in a Frustrated Lattice Due to Charge Ordering: A Scenario for Pairing in Layered Cobaltates
Autorzy:
Wróbel, P.
Suleja, W.
Powiązania:
https://bibliotekanauki.pl/articles/2047314.pdf
Data publikacji:
2007-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
74.20.Mn
75.50.Ee
Opis:
The mechanism of pairing-symmetry selection in the weakly electron doped t-J model on the honeycomb lattice has been analyzed. The discussion of that problem has been motivated by some recent suggestions that due to charge ordering which may take place in the unconventional superconductor Na$\text{}_{x}$CoO$\text{}_{2}$· yH$\text{}_{2}$O at doping levels near x=1/3 the physics of CoO$\text{}_{2}$ planes may be effectively described in terms of a model for a weakly electron doped antiferromagnet on the honeycomb lattice. In the current publication the main emphasis has been put on reviewing experimental and theoretical work, the results of which support the scenario of charge order. In the calculation, the so-called string picture has been used. It has been demonstrated that spin fluctuations may induce in the honeycomb lattice the formation of an unconventional two-particle bound state. Upon the condensation of bound particles this mechanism may give rise to unconventional pairing. The critical value of the ratio J/t which is sufficient to induce binding has not been evaluated. It has been assumed instead that in the case of cobaltates some additional isotropic attractive interaction, for example phonon mediated, is active. Despite that the exchange of spin fluctuations is not a dominating interaction, it selects the symmetry of the paired state because it is anisotropic. C$\text{}_{3v}$ is the relevant point group for the t-J model on the honeycomb lattice. It has been shown that the bound state of two additional electrons doped to the half-filled antiferromagnetically ordered system has zero total momentum and p-wave symmetry of the irreducible representation E. The expected paired state is a mixture of a singlet and a triplet because the honeycomb lattice does not possess the inversion symmetry.
Źródło:
Acta Physica Polonica A; 2007, 111, 4; 563-572
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Studies of S=1 Heisenberg Planar Antiferromagnetic Chain Ni(C$\text{}_{11}$H$\text{}_{10}$N$\text{}_{2}$O)$\text{}_{2}$Ni(CN)$\text{}_{4}$
Autorzy:
Čizmár, E.
Černák, J.
Orendáč, M.
Herrmannsdörfer, T.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/2013230.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
71.20.Be
75.50.Ee
Opis:
In this paper we discuss the results of experimental studies of specific heat and magnetic susceptibility of chain compound Ni(C$\text{}_{11}$H$\text{}_{10}$N$\text{}_{2}$O)$\text{}_{2}$Ni(CN)$\text{}_{4}$. We have observed a Schottky type anomaly at T=2.2 K in a temperature dependence of specific heat and the compound was identified as a S=1 Heisenberg antiferromagnetic chain with the subcritical exchange coupling D/k$\text{}_{B}$=5 K, D/|J|=5.2 and the strong in-plane anisotropy E/k$\text{}_{B}$=2.8 K. It has been found that the in-plane anisotropy affects the region of validity of a diluted exciton model [1] and a strong coupling model [2] for S=1 Heisenberg chains with the strong planar anisotropy. The analysis suggests that the in-plane anisotropy should be considered in any attempt to find a compound potentially located in the boundary of Haldane and "large-D" phases.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 579-582
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Origin of EPR Signals in SrCuO$\text{}_{2}$ Ceramics
Autorzy:
Augustyniak-Jabłokow, M. A.
Yablokov, Yu. V.
Ivanova, T. A.
Jacyna-Onyszkiewicz, I.
Shustov, V. A.
Powiązania:
https://bibliotekanauki.pl/articles/2043623.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
76.30.Fc
81.05.Je
Opis:
The origin and thermal evolution of the EPR signals in SrCuO$\text{}_{2}$ ceramics are studied. It has been shown that the EPR signals observed in this ceramic material are due to contamination with other phases. The axial signal is due to SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O, which is a product of water reactions with SrCuO$\text{}_{2}$.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 345-351
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Study of Water Induced Decomposition of the SrCuO$\text{}_{2}$ and Sr$\text{}_{2}$CuO$\text{}_{3}$ Ceramics Surface. The Role of Carbon Dioxide
Autorzy:
Augustyniak-Jabłokow, M. A.
Yablokov, Yu. V.
Jacyna-Onyszkiewicz, I.
Ivanova, T. A.
Shustov, V. A.
Powiązania:
https://bibliotekanauki.pl/articles/2047737.pdf
Data publikacji:
2007-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
76.30.Fc
81.05.Je
Opis:
Processes of SrCuO$\text{}_{2}$ and Sr$\text{}_{2}$CuO$\text{}_{3}$ ceramics decomposition induced by contact with water and carbon dioxide were studied by EPR. The dominant signals in the spectra were found to originate from Sr$\text{}_{2}$Cu(OH)$\text{}_{6}$ (for Sr$\text{}_{2}$CuO$\text{}_{3}$) and SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O (for SrCuO$\text{}_{2}$) compounds. The thermally induced conversion of SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O into Sr$\text{}_{2}$Cu(OH)$\text{}_{6}$ was analysed, and its product CuO was found to exist in the nanocrystalline form. The presence of CO$\text{}_{2}$, reacting with Sr(OH)$\text{}_{2}$, was shown to modify the decomposition process leading to the appearance of SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O, some hydroxycarbonates and Cu(OH)$\text{}_{2}$ on the surface of ceramics studied. At temperatures higher than 300ºC CuO reacts back with Sr(OH)$\text{}_{2}$. For the samples being in contact with atmospheric moisture this compound, deposited on a surface of SrCuO$\text{}_{2}$, decomposes to Sr$\text{}_{2}$Cu(OH)$\text{}_{6}$. The presence of the antiferromagnetic compounds Cu(OH)$\text{}_{2}$, CuO, and Cu$\text{}_{2}$[(OH)$\text{}_{2}$CO$\text{}_{3}$] in the samples can influence the results of magnetic measurements of the studied ceramics.
Źródło:
Acta Physica Polonica A; 2007, 112, 3; 525-536
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Characterization of Magnetoferritin
Autorzy:
Mitróová, Z.
Melníková, L.
Kováč, J.
Timko, M.
Kopčanský, P.
Powiązania:
https://bibliotekanauki.pl/articles/1429123.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.50.Ee
75.60.Ej
75.50.Tt
Opis:
The paper presents detailed experimental study of synthesis and characterization a bioinorganic magnetic molecule - magnetoferritin. Magnetoferritin with loading of iron ions per protein molecule in the range from 300 to 3000 was prepared. Size distribution analysis (transmission electron microscopy, dynamic light scattering) shows spherical nanoparticles with particle size distribution from 2 to 12 nm, and hydrodynamic diameter from 12 to 25 nm. The thermomagnetic curves measured after cooling the sample in zero field (zero-field cooling) and under the presence of the measurement field (field cooling) show superparamagnetic behavior with the blocking temperature $T_{b}$ from 22 to 60 K and the magnetization loops measured below $T_{b}$ (at 2 K) show the hysteresis with coercive field from 20 to 30 kA/m depending on the concentration of the magnetic nanoparticles.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1318-1320
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Pressure on Magnetic Properties of Hexacyanochromates
Autorzy:
Mitróvá, Z.
Maťaš, S.
Mihalik, M.
Zentková, M.
Arnold, Z.
Kamarád, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813813.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.50.Ee
75.50.Gg
75.50.Xx
Opis:
We present the study of pressure effect on magnetic properties of $TM^{2+}_3[Cr^{III}(CN)_6]_2 \cdot nH_2O$ ferrimagnets and ferromagnets (TM = Cr and Co) under pressures up to 0.9 GPa. Applied pressure strengthens super-exchange interaction in $Cr^{2+}$-prussian blue analogues with dominant antiferromagnetic interaction $J_{AF}$ leading to increase in the Curie temperature $T_C$ (ΔT_c/Δp = 29.0 K/GPa) and reduces $T_C$ of $Co^{2+}$-prussian blue analogues with dominant ferromagnetic interaction $J_F$ (Δ$T_c$/Δp = -1.8 K/GPa). The rise of $J_{AF}$ interaction is attributed to the enhanced value of the single electron overlapping integral S. On the other hand, the applied pressure slightly affects bonding angles between magnetic ions mediated by the cyano-bridge and reduces the strength of magnetic coupling. Changes of the magnetization curve with pressure can be attributed to changes of magnetic anisotropy. The reduction of magnetization with pressure observed on $Cr^{2+}$-prussian blue analogues can be explained by pressure induced transition from $Cr^{2+}$ high spin state to $Cr^{2+}$ low spin state. All pressure induced changes are reversible.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 469-472
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of RIrSi (R = Tb, Dy, and Ho) Compounds
Autorzy:
Duraj, R.
Szytuła, A.
Powiązania:
https://bibliotekanauki.pl/articles/1400158.pdf
Data publikacji:
2013-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.40.Gb
75.47.Np
75.50.Ee
Opis:
The magnetic data for the polycrystalline samples of RIrSi (R = Tb, Dy and Ho) compounds are reported. These compounds are antiferromagnets with the Néel temperatures equal to 32 K (R = Tb), 7.0 K (R = Dy) and 4.8 K (R = Ho), respectively. The external magnetic field induces the one step for TbIrSi and two step for DyIrSi and HoIrSi metamagnetic phase transitions. The values of the critical field as Néel temperatures decrease with increase of the number of 4f electrons. The magnetic phase diagrams (H, T) are determined.
Źródło:
Acta Physica Polonica A; 2013, 123, 4; 773-776
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heisenberg Antiferromagnet on a 1/7-Depleted Triangular Lattice
Autorzy:
Schulenburg, J.
Richter, J.
Betts, D. D.
Powiązania:
https://bibliotekanauki.pl/articles/2013992.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Hk
75.10.Jm
75.40.Mg
75.50.Ee
Opis:
Based on the triangular lattice and its depletions there are three simple frustrated antiferromagnetic Heisenberg models in two dimensions. The first two, the triangular and kagomé lattices, have been examined in the recent past. The triangular lattice seems to have a long range order whereas the kagomé does not show the long range order. But these results are still controversial. This work is concentrated on a third type of this lattice family in order to improve the understanding of the connection between the long range order and coordination number in low dimensional systems. Bets has described the geometric properties of this lattice. It has a coordination number 5, which lies precisely between coordination numbers 6 and 4 of the other two lattices. The low-lying spectra and the correlation functions of finite lattices have been examined to discuss the possibility of a long range ordered ground state in the 1/7-depleted triangular lattice. The low-lying spectrum is generated by an exact diagonalization, and the tower of states behavior points to a long range ordered ground state.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 971-974
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhanced magnetocaloric effect due to selective dilution in a triangular ising antiferromagnet
Autorzy:
Borovský, M.
Žukovič, M.
Powiązania:
https://bibliotekanauki.pl/articles/1054817.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
75.50.Ee
75.30.Sg
05.10.Ln
Opis:
We employ an effective-field theory with correlations in order to study a magnetocaloric effect on a triangular Ising antiferromagnet, which is selectively diluted by non-magnetic impurities on one of the three sublattices. Such a dilution generally relieves massive degeneracy in our system and therefore the ground-state entropy diminishes and the magnetocaloric effect weakens at low temperatures. However, at relatively higher temperatures we can observe significantly enhanced negative isothermal entropy changes for the sublattice concentration p_A=0.8.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 645-647
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Pressure on Magnetic Properties of $TM_3[Cr(CN)_6]_2 \cdot nH_2O$ Nanoparticles
Autorzy:
Zentko, A.
Zentková, M.
Kavečanský, V.
Mihalik, M.
Mitróová, Z.
Arnold, Z.
Kamarád, J.
Cieslar, M.
Zeleňák, V.
Powiązania:
https://bibliotekanauki.pl/articles/1813843.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.50.Ee
75.50.Gg
75.50.Xx
Opis:
Effect of pressure on magnetic properties of magnetic nanoparticles, based on Prussian blue analogues, were studied in pressures up to 1.2 GPa. The $Mn_3[Cr(CN)_6]_2 \cdot nH_2O$ and $Ni_3[Cr(CN)_6]_2 \cdot nH_2O$ nanoparticles were prepared by reverse micelle technique. Transmission electron microscopy images show nanoparticles with average diameter of about 3.5 nm embedded in an organic matrix. The characteristic X-ray peaks of nanoparticles are more diffused and broader. Systems of nanoparticles behave as systems of interacting magnetic particles. The Curie temperature $T_C$ is reduced from $T_C$ = 56 K for Ni-Prussian blue analogues to $T_C$ = 21 K for Ni-nanoparticles system and from $T_C$ = 65 K for Mn-Prussian blue analogues to $T_C$ = 38 K for Mn-nanoparticles system. One can explain this reduction of the Curie temperature and of the saturated magnetization $μ_s$ by dispersion of nanoparticles in an organic matrix i.e. by a dilution effect. Applied pressure leads to a remarkable increase in $T_C$ for system of Mn-nanoparticles (Δ$T_C$/Δp = +13 K/GPa) and to only slight decrease in $T_C$ for system of Ni-nanoparticles (Δ$T_C$/Δp = -3 K/GPa). The pressure effect follows behavior of the mother Prussian blue analogues under pressure. The increase in saturated magnetization, attributed to compression of the organic matrix, is very small.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 489-493
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic Susceptibility in Thin Films with Antiferromagnetic Coupling between Layers
Autorzy:
Świrkowicz, R.
Powiązania:
https://bibliotekanauki.pl/articles/1952834.pdf
Data publikacji:
1996-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Lp
75.30.Cr
75.30.Ds
75.50.Ee
Opis:
The dynamic susceptibility of the system with antiferromagnetic coupling between layers is investigated within the framework of the multiband model using the equation of motion with random phase approximation. Calculations are performed in the mixed Bloch-Wannier representation and a general form for χ is found. The susceptibility can be written in terms of two-particle Green's functions expressed in the local coordinate system with the z axis aligned along the local magnetization. The expression depends on an angle between the magnetization direction in a given layer and the crystal axis. Preliminary numerical calculations are performed for two systems: ultrathin Cr film and Fe/Cr multilayer structure. Imaginary part of the susceptibility corresponding to different layers is calculated and spin waves are discussed.
Źródło:
Acta Physica Polonica A; 1996, 90, 6; 1215-1226
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exchange Interactions in a Low-Dimensional Magnetic System $Cu(H_{2}O)_{2}(en)SO_{4}$
Autorzy:
Sýkora, R.
Legut, D.
Wdowik, U.
Powiązania:
https://bibliotekanauki.pl/articles/1366514.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Hk
75.10.-b
75.40.Cx
75.50.Ee
Opis:
We report a theoretical ab-initio investigation of the exchange interaction between Cu atoms in $Cu(H_{2}O)_{2}(en)SO_{4}$, en=$C_{2}H_{8}N_{2}$(ethylenediamine), an insulating magnetic material. Unlike previous experimental studies which describe the system as a quasi-two-dimensional antiferromagnet, our results, based on the mapping of the system onto an effective Heisenberg model, suggest a quasi-one-dimensional character of magnetism, with the exchange coupling between the Cu atoms being propagated along a zigzag line, lying in the crystal's bc plane and connecting the Cu atoms through the N atoms. Furthermore, we report the calculated positions of the H atoms that have not been provided in experimental papers.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 50-51
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi-Step Magnetic Phase Transition in $CeRh_3Si_2$ Studied by Specific Heat Measurements
Autorzy:
Pikul, A.
Kaczorowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/1810486.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Mb
75.50.Ee
75.30.Kz
65.40.Ba
Opis:
High-quality single crystal of a novel cerium silicide $CeRh_3Si_2$, crystallizing with the orthorhombic $ErRh_3Si_2$-type structure, was grown by the Czochralski pulling method and studied by means of specific heat measurements. The antiferromagnetic ordering of the compound manifests itself as a pronounced lambda-shaped anomaly at $T_N$ = 4.72(3) K, and is followed by a spike-shaped anomaly due to spin reorientation at $T_t$ = 4.48(2) K, in good agreement with the previously reported magnetic susceptibility data. Both transitions are very sensitive to applied magnetic field - they split into four separate anomalies, which independently shift to lower temperatures with rising field. Several scenarios are proposed as possible explanations of the multi-step character of the magnetic ordering in $CeRh_3Si_2$.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 235-237
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of the $\text{}^{119}$Sn Mössbauer-Effect Spectroscopy in the Investigation of Spin-Density-Waves in Chromium
Autorzy:
Dubiel, S. M.
Powiązania:
https://bibliotekanauki.pl/articles/1929384.pdf
Data publikacji:
1993-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Fv
75.50.Ee
76.80.+y
75.25.+z
Opis:
Application of $\text{}^{119}$Sn Mossbauer-effect spectroscopy in an investigation of spin-density-waves in chromium in terms of model calculations as well as of measurements on real samples is presented.
Źródło:
Acta Physica Polonica A; 1993, 84, 1; 83-100
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity and Quantum Critical Behavior in Cr_{100-z}Os_z
Autorzy:
Prinsloo, A.
Sheppard, C.
Fernando, P.
Powiązania:
https://bibliotekanauki.pl/articles/1398328.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Fv
74.70.Ad
74.40.Kb
Opis:
The magnetic phase diagrams of Cr alloys with group-8 metals, such as Re and Ru, show interesting properties. These include quantum critical and superconducting behavior. In order to extend these investigations this paper reports on the physical properties and the magnetic phase diagram of the $Cr_{100-z}Os_{z}$ system, investigated in a concentration range of 2 ≤ z ≤ 30.6. Structural analysis indicate that samples with z<22 have a bcc structure, while those with z>22 include a cubic A15-type structure. Transport and magnetic property measurements indicate that the antiferromagnetic phase disappears at z ≈ 14 and that samples with concentrations z ≥ 12.2 show superconducting behavior. The magnetic phase diagram of $Cr_{100-z}Os_{z}$ is constructed from the Néel and superconducting transition temperatures obtained from various measurements. The commensurate spin-density-wave to paramagnetic phase line decreases sharply for z>4. Fitting parameters of a power law fit to the commensurate spin-density-wave to paramagnetic phase line indicate possible quantum critical behavior. Present results suggest that this phase line terminates in a superconducting dome near a magnetic quantum critical point, similar to that observed in certain heavy fermion systems, but not previously reported for other Cr alloys.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1132-1134
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diagonalization of a Bosonic Quadratic Form Using CCM: Application on a System with Two Interpenetrating Square Lattice Antiferromagnets
Autorzy:
Krüger, S. A.
Schmalfuss, D.
Richter, J.
Powiązania:
https://bibliotekanauki.pl/articles/2013979.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Ds
31.15.Dv
42.50.Lc
Opis:
While the diagonalization of a quadratic bosonic form can always be done using a Bogolyubov transformation, the practical implementation for systems with a large number of different bosons is a tedious analytical task. Here we use the coupled cluster method to exactly diagonalise such complicated quadratic forms. This yields to a straightforward algorithm which can easily be implemented using computer algebra even for a large number of different bosons. We apply this method on a Heisenberg system with two interpenetrating square lattice antiferromagnets, which is a model for the quasi-2D antiferromagnet Ba$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{4}$Cl$\text{}_{2}$. Using a four-magnon spin wave approximation we get a complicated Hamiltonian with four different bosons, which is treated with coupled cluster method. Results are presented for magnetic ground state correlations.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 951-954
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Isothermal Entropy Change and Adiabatic Change of Temperature of the Antiferromagnetic Spin-1/2 Ising Octahedron and Dodecahedron
Autorzy:
Karľová, K.
Strečka, J.
Madaras, T.
Powiązania:
https://bibliotekanauki.pl/articles/1032208.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.10.Hk
75.50.Ee
75.50.Xx
Opis:
The spin-1/2 Ising octahedron and dodecahedron with a unique antiferromagnetic interaction display an outstanding magnetization jump at zero magnetic field, which consequently leads to a giant magnetocaloric effect during the adiabatic demagnetization. In the present work we report temperature dependences of two basic magnetocaloric response functions: the isothermal entropy change and the adiabatic change of temperature. It is shown that the Ising octahedron and dodecahedron generally exhibit a large negative isothermal entropy change upon increase of the magnetic field, which serves in evidence of their cooling performance.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 630-632
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Size effects in antiferromagnetic NiO nanoparticles
Autorzy:
Baran, S.
Hoser, A.
Penc, B.
Szytuła, A.
Powiązania:
https://bibliotekanauki.pl/articles/1075485.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.F-
75.30.Cr
75.47.Lx
75.50.Ee
Opis:
X-ray and neutron diffraction as well as magnetometric methods were used in order to investigate crystal and magnetic structure together with magnetic properties of nickel oxide NiO obtained from thermal decomposition of Ni(OH)₂. It has been found that crystal unit cell volume and crystal unit cell deformation parameter decrease with increasing decomposition temperature T_{d} while grain size increases. The results of magnetization, magnetic susceptibility and neutron diffraction measurements reveal a formation of antiferromagnetic order with uncompensated magnetic moment below the Néel temperature. Magnetization together with coercive field decreases with increasing T_{d}. The neutron diffractogram of sample obtained at 240°C indicates broadening of both the peaks of nuclear and magnetic origin. The magnetic ordering may be described by a propagation vector k=[½,½,½].
Źródło:
Acta Physica Polonica A; 2016, 129, 1; 35-39
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Temperature Properties of Ising Antiferromagnet on a Stacked Triangular Lattice
Autorzy:
Žukovič, M.
Mižišin, L.
Bobák, A.
Powiązania:
https://bibliotekanauki.pl/articles/1199547.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
64.60.De
75.10.Hk
75.50.Ee
Opis:
An Ising antiferromagnet on a stacked triangular lattice in zero field is studied by Monte Carlo simulations, focusing on the character of the low-temperature phase and the effect of the relative strength of the exchange interaction in the stacking direction α. Our results support the presence of the 3D Wannier phase, with the sublattice magnetization structure (m, -m, 0) and power-law decaying m with the lattice size. The extent of this low-temperature phase shrinks with decreasing α, however, it appears even at very low values if it is accessed from higher temperatures by sufficiently slow cooling.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 40-41
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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