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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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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 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
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