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Tytuł:
Structural and Magnetic Properties of the $PrNi_{1-x}Cu_{x}Al$ Series
Autorzy:
Fikáček, J.
Javorský, P.
Klicpera, M.
Šantavá, E.
Powiązania:
https://bibliotekanauki.pl/articles/1534261.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
Opis:
Polycrystalline samples of $PrNi_{1-x}Cu_{x}Al$ series were studied by X-ray diffraction, magnetization and specific heat. The hexagonal ZrNiAl-type structure is preserved in the whole series. Compounds with x up to 0.4 order antiferromagnetically with the Néel temperatures between 3 and 5 K. The rest of the compounds (x = 0.5-0.9) exhibits a transition into a spin glass state below the freezing temperatures around 4 K. The analysis of the specific heat data reveals a quasi-doublet ground state well separated from higher crystal field levels in the whole series.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 884-885
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Specific Heat of Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te
Autorzy:
Górska, M.
Łusakowski, A.
Jędrzejczak, A.
Gołacki, Z.
Anderson, J. R.
Balci, H.
Powiązania:
https://bibliotekanauki.pl/articles/2038143.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.-d
75.40.Cx
Opis:
The temperature dependence of the magnetic specific heat was studied experimentally and theoretically in the semimagnetic semiconductor Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te for x=0.027 and x=0.073, over the temperature range from 0.5 K to 15 K, in magnetic fields up to 2 T. In zero magnetic field at about 2 K there was a broad maximum in the magnetic specific heat, which was much higher than that predicted by the model of superexchange interaction between nearest neighbors; the maximum values increased with magnetic field. The experimental data were analyzed in the framework of a model which takes into account the spin splitting of the ground state of a single Eu2+ ion in the presence of local lattice distortions in the Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te mixed crystal. The model describes well the experimental data, especially for lower x-values, where the contribution from singlets dominates.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 631-636
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Phonon Dispersion in Alkali Metals
Autorzy:
Gajjar, P. N.
Thakore, B. Y.
Patel, H. K.
Jani, A. R.
Powiązania:
https://bibliotekanauki.pl/articles/1933617.pdf
Data publikacji:
1995-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.25.Cx
63.20.Dj
Opis:
In the present paper, the calculation of the phonon dispersion relations for alkali metals to second order in a local pseudopotential is discussed in terms of the real-space sum. Different forms of dielectric functions are employed to judge the varying effects of exchange and correlation on the phonon frequencies. The quantitative agreement of phonon frequencies for the alkali metals reflects, satisfactorily, the experimental trend.
Źródło:
Acta Physica Polonica A; 1995, 88, 3; 489-502
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Transitions in Magnetic and Superconducting Systems with Fluctuating Valence. Chemical Potential Evidence
Autorzy:
Gosławska, E.
Matlak, M.
Eid, Kh.
Powiązania:
https://bibliotekanauki.pl/articles/2013336.pdf
Data publikacji:
2000-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.40.Cx
Opis:
We investigate the critical behaviour of the chemical potential and average occupation numbers using the extended s -f model with intersite Cooper pairing for systems with fluctuating valence. The model is able to describe phase transitions from normal ferromagnet to normal paramagnet at $T=T_{C}$, from superconducting paramagnet to normal paramagnet at $T=T_{S}$, as well as reentrant phase transitions with three critical temperatures $T_{S_{1}}, T_{C}$ and $T_{S_{2}} (T_{S_{1}} < T_{C} < T_{S_{2}})$. Present investigation, as well as recent results obtained for another models suggest one-to-one correspondence between critical temperatures of the system and kinks appearing in the temperature dependence of the chemical potential and average occupation numbers. This, in turn, indicates a possibility to apply the measurement of the chemical potential vs. temperature as an experimental universal tool when looking for phase transitions in solids.
Źródło:
Acta Physica Polonica A; 2000, 97, 4; 713-718
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Manifestation of Spin-Glass-Like Behavior in the Organometallic Magnet
Autorzy:
Dyakonov, V. P.
Arciszewska, M.
Dobrowolski, W.
Szewczyk, A.
Szymczak, H.
Aksymentieva, E.
Varyukhin, V.
Zubov, E.
Gutowska, M. U.
Powiązania:
https://bibliotekanauki.pl/articles/2013705.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.40.Cx
Opis:
Ac susceptibility (χ$\text{}_{ac}$) and dc magnetization (M$\text{}_{dc}$) of the organometallic magnet Na[FeO$\text{}_{6}$(C$\text{}_{10}$H$\text{}_{8}$N)$\text{}_{3}$] have been studied in temperature range of 4.2-200 K, in an external magnetic field up to 16 kOe. Some peculiarities of the χ$\text{}_{ac}$ and M $\text{}_{dc}$ behavior, which are characteristic of spin-glasses, e.g. cusps in the susceptibility and zero-field-cooled magnetization, an irreversibility between the field-cooled and zero-field-cooled magnetization and dependences of the T$\text{}_{cusp}$ temperature on the frequency and the intensity of the magnetic field, were observed at low temperatures.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 863-866
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Energy Spectrum and Thermodynamics of Spin-1/2 XX Chain with Ising Impurities
Autorzy:
Ezerskaya, E.
Powiązania:
https://bibliotekanauki.pl/articles/1032134.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.40.Cx
Opis:
The energy spectrum and peculiarities of field and temperature dependences of the basic thermodynamic characteristics of the finite spin-1/2 XX chain closed by one zz (Ising) bond and open ends XX-chain with two zz-impurities at the both ends have been investigated.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 928-930
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transition from Mixed-Valence to Trivalent Cerium State in Ce(Ni,Cu)Al Series
Autorzy:
Čermák, P.
Javorský, P.
Šantavá, E.
Powiązania:
https://bibliotekanauki.pl/articles/1534620.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.30.Mb
Opis:
In this work we present the study of the part of Ce(Ni,Cu)Al series from the pure CeNiAl to 30% of copper concentration, which illustrates the transition from mixed-valence state of CeNiAl to the trivalent state in CeCuAl. The work is based on X-ray diffraction, magnetization and specific heat measurement. The results indicate smooth transition between the mixed-valence and trivalent cerium state. The specific-heat data reveal increase of the Sommerfeld γ coefficient with copper concentration.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 926-928
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of the Experimental Molecular-Based Ring-Shaped Nanomagnets
Autorzy:
Antkowiak, M.
Kozłowski, P.
Musiał, G.
Florek, W.
Kamieniarz, G.
Esposito, F.
Powiązania:
https://bibliotekanauki.pl/articles/1534905.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.40.Mg
Opis:
Quantum transfer matrix technique and numerically exact diagonalization method are applied to the Heisenberg spin systems to model ring-shaped molecules. Two cases are investigated: (i) a dozen of S = 1 spins with additional biquadratic exchange and (ii) a dimetallic molecule $Cr_7Cd$, where it is assumed that exchange anisotropy is determined in a local coordination system. In the latter case the calculated susceptibility is compared with experimental results.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 965-966
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Effect in Geometrically Frustrated Magnetic Compound $HoB_{12}$
Autorzy:
Snyman, J.
Flachbart, K.
Gabani, S.
Reiffers, M.
Shitsevalova, N.
Siemensmeyer, K.
Strydom, A.
Powiązania:
https://bibliotekanauki.pl/articles/1534216.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.40.Cx
Opis:
The magnetocaloric effect of frustrated antiferromagnetic $HoB_{12}$ is calculated. The isothermal entropy change Δ S characterising the magnetocaloric effect shows a small positive change upon magnetisation below the transition temperature $T_{N}$, indicating a small inverse magnetocaloric effect. At $T_{N}$, Δ S shows clear scaling behaviour with the applied magnetic field. The adiabatic temperature change Δ T shows paramagnetic behaviour above $T_{N}$, despite strong magnetic correlations that persist in this temperature region. The adiabatic temperature change calculated for $HoB_{12}$ is appreciable.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 873-874
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Specific Heat of the Mixed Spin-1/2 and Spin-S Ising Model with a Rope Ladder Structure
Autorzy:
Kiššová, J.
Strečka, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813792.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
75.40.Cx
Opis:
The mixed spin-1/2 and spin-S (S>1/2) Ising model on a rope ladder is examined by combining two exact analytical methods. By the decoration-iteration mapping transformation, this mixed-spin system is firstly transformed to a simple spin-1/2 Ising model on the two-leg ladder, which is then exactly solved by the standard transfer-matrix method. The thermal variations of the zero-field specific heat are discussed in particular.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 445-448
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zero Temperature Magnetic Frustration in Nona-Membered s=3/2 Spin Rings with Bond Defect
Autorzy:
Antkowiak, M.
Kozłowski, P.
Kamieniarz, G.
Powiązania:
https://bibliotekanauki.pl/articles/1427128.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.10.Jm
Opis:
Zero-temperature limits of the local and global thermodynamic quantities in the nine-membered antiferromagnetic s=3/2 spin ring are investigated by means of numerical exact diagonalization. An anisotropic Heisenberg model with tunable bond defect reflecting continuously varying topology (from closed to open ring) is exploited. The frustrated and non-frustrated phases are identified in the ground-state phase diagram determined by a bond-defect strength and magnetic field. Near the phase boundaries significance of the thermal fluctuations affecting the estimates of the local magnetic quantities found earlier at T=1 K is revealed. For the global quantities the effects of thermal fluctuations are found much weaker. A sequence of the local magnetic moments is analysed and their experimental verification at the edges of the non-frustrated and within the entire frustrated phase is suggested at sufficiently low temperature.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1102-1104
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Specific Heat and Magnetism of $LuFe_6Al_6$
Autorzy:
Svoboda, P.
Andreev, A.
Šantavá, E.
Šebek, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813662.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
65.40.Ba
Opis:
Here we present the results of the zero-field specific heat study of the $LuFe_6Al_6$ single crystal. The specific heat data were analyzed as a sum of the phonon, electronic, and magnetic contributions, respectively. The analysis of the phonon part involves three acoustic and 36 optical branches, respectively, all of them corrected for the anharmonicity. The magnetic part of the specific heat was obtained by subtracting the electronic and the phonon part from the experimental specific heat and the magnetic entropy was calculated.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 307-310
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lattice Heat Capacity in RTAl (R = Y, Lu;T = Ni, Cu, Pd) Compounds
Autorzy:
Daniel, P.
Javorský, P.
Prchal, J.
Daniš, S.
Šantavá, E.
Powiązania:
https://bibliotekanauki.pl/articles/1813674.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.Ba
75.40.Cx
Opis:
We present analysis of the specific heat of the RTAl (R = Y, Lu;T = Cu, Ni, Pd) compounds. We focus on the lattice contribution and analyze the dependence of all the characteristic parameters in the Debye and Einstein models on the atomic masses and interatomic distances.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 331-334
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat Capacity and Susceptibility of $CeCu_4Al$
Autorzy:
Reiffers, M.
Gažo, E.
Timko, M.
Kowalczyk, A.
Toliński, T.
Andrzejewski, B.
Šebek, J.
Šantavá, E.
Powiązania:
https://bibliotekanauki.pl/articles/1813775.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.30.Mb
Opis:
The heat capacity in the applied magnetic field up to 9 T, susceptibility and magnetization of polycrystalline $CeCu_4Al$ are presented. The determined electronic heat capacity coefficient γ= 210 mJ $mol^{-1} K^{-2}$ confirmed heavy fermion character of this compound. Magnetic ordering was not observed down to 0.5 K. Magnetic properties confirm these observations.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 425-428
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low Temperature Anomalies in the Specific Heat and Magnetic Susceptibility of $Na_{0.7}CoO_2$ Samples
Autorzy:
Baran, A.
Zorkovská, A.
Feher, A.
Šebek, J.
Šantavá, E.
Hejtmánek, J.
Veverka, M.
Bradarić, I.
Ružička, M.
Powiązania:
https://bibliotekanauki.pl/articles/1813849.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
72.80.Ga
Opis:
We present a comparative study of $Na_{0.7}CoO_2$ samples obtained from three different sources and prepared by different methods. The specific heat and magnetic susceptibility measurements in the temperature range 2-300 K show substantial influence on the observed anomalies, which underlines that the system is extremely sensitive to preparation protocols.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 495-498
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermodynamics of Ising Ferromagnet Studied by the Real-Space Renormalization Group Method
Autorzy:
Reich, W.
Piotrkowska, K.
Esposito, U.
Caramico D'Auria, A.
Powiązania:
https://bibliotekanauki.pl/articles/1929558.pdf
Data publikacji:
1993-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.Ak
75.40.Cx
Opis:
The critical exponents of the 3D Ising model were calculated in the approximation of the fourth-order cumulant expansion. Thermodynamic functions in the high-temperature range are obtained.
Źródło:
Acta Physica Polonica A; 1993, 84, 2; 275-278
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Study of Phase Diagrams for Reentrant Superconducting Er$\text{}_{1-x}$Ho$\text{}_{x}$X, Er$\text{}_{1-x}$Gd$\text{}_{x}$X, Er$\text{}_{1-x}$Tm$\text{}_{x}$X, Ho$\text{}_{x}$Lu$\text{}_{1-x}$X, and Sm$\text{}_{1-x}$Er$\text{}_{x}$X (X = Rh$\text{}_{4}$B$\text{}_{4}$) Alloys
Autorzy:
Gosławska, E.
Matlak, M.
Powiązania:
https://bibliotekanauki.pl/articles/2013024.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.40.Cx
Opis:
We consider a simplified version of the s-f model, supplemented by the intersite Cooper pairs interaction between conduction electrons with opposite spins to investigate ferromagnetic and superconducting properties of an alloy Re$\text{}_{1-x}^{(1)}$Re$\text{}_{x}^{(2)}$X (Re$\text{}^{(1),(2)}$ - rare earth elements, X = Rh$\text{}_{4}$B$\text{}_{4}$) using the virtual crystal approximation. For a suitable choice of the model parameters we can reproduce the phase boundaries of the experimentally measured phase diagrams for Er$\text{}_{1-x}$Ho$\text{}_{x}$X, Er$\text{}_{1-x}$Gd$\text{}_{x}$ X, Er$\text{}_{1-x}$Tm$\text{}_{x}$X, Ho$\text{}_{x}$Lu$\text{}_{1-x}$X, and Sm$\text{}_{1-x}$Er$\text{}_{x}$X alloys.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 415-418
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Susceptibility of Sr$\text{}_{2}$CuO$\text{}_{3}$ and SrCu$\text{}_{2}$O$\text{}_{3}$
Autorzy:
Johnston, D. C.
Powiązania:
https://bibliotekanauki.pl/articles/1953177.pdf
Data publikacji:
1997-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.Jt
74.25.Ha
75.40.Cx
Opis:
The observed magnetic susceptibility χ$\text{}^{obs}$(T) data of Ami et al. for the linear-chain cuprate Sr$\text{}_{2}$CuO$\text{}_{3}$ are re-analyzed in terms of recent theory of Eggert et al. for the spin susceptibility χ(T) of the spin S=1/2 linear-chain Heisenberg antiferromagnet, which yielded the Cu-Cu exchange constant J/k$\text{}_{B}$=2150 K. Values for J', the exchange constant in the rungs, and J, that in the legs, were estimated for the S=1/2 two-leg ladder compound SrCu$\text{}_{2}$O$\text{}_{3}$, using the χ(T) data of Azuma et al. The analyses suggest that J'/J ≈ 0.5, contrary to the expectation that J'/J ≈ 1, and that J/k$\text{}_{B}$ is very large ( ≈ 2000 K), similar to that in Sr$\text{}_{2}$CuO$\text{}_{3}$.
Źródło:
Acta Physica Polonica A; 1997, 91, 1; 181-189
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:
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:
Magnetic Characteristics of the System of Exchange Coupled Layers
Autorzy:
Urbaniak-Kucharczyk, A.
Machowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2013215.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.70.Ak
75.30.-m
75.40.Cx
Opis:
Using the Green function method it is shown that the deviation of the Curie temperature from its value calculated for continuous layers is related to the absolute value of the interlayer coupling parameter. The dependence of spin wave stiffness parameter on the interlayer exchange coupling is also found.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 543-546
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Field-Induced Slow Magnetic Relaxation in Mn₉W₆ Cluster-Based Compound
Autorzy:
Konieczny, P.
Pełka, R.
Chorazy, S.
Podgajny, R.
Sieklucka, B.
Wasiutyński, T.
Powiązania:
https://bibliotekanauki.pl/articles/1032251.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Xx
75.40.Cx
75.50.Gg
Opis:
Magnetic measurements of a three-dimensional (3D) molecular magnet built of Mn₉[W(CN)₈]₆ clusters have been carried out to study its static and dynamic properties. Measurements of ac susceptibility in the presence of static magnetic field revealed slow magnetic relaxations. It was found that for the 120 Hz wave frequency the optimal static field which maximizes the imaginary component of the ac susceptibility is about 500 Oe.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 884-886
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:
Giant Magnetocaloric Effect in Manganites
Autorzy:
Szymczak, R.
Kolano, R.
Kolano-Burian, A.
Dyakonov, V.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/1550566.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.30.Sg
75.40.Cx
Opis:
In this review we briefly discuss the magnetocaloric properties of the manganites. It is evidenced that the maximum entropy change observed in manganites exceeds that of gadolinium (the prototype material for room temperature refrigerators). For the manganites characterized by second-order magnetic phase transitions the scaling hypothesis is discussed. It is shown that simple phenomenological model with only one fitting parameter, presented in this paper, satisfactorily describes experimental observations.
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 203-206
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Temperature Specific Heat and Magnetocaloric Effect in $RCu_2Ge_2$ (R = Dy-Tm) Compounds
Autorzy:
Gondek, Ł.
Kaczorowski, D.
Pikul, A.
Szytuła, A.
Powiązania:
https://bibliotekanauki.pl/articles/1419609.pdf
Data publikacji:
2012-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
75.30.Sg
75.40.Cx
Opis:
The magnetocaloric effect in $RCu_2Ge_2$ (R = Dy-Tm) was investigated by means of specific heat measurements. The compounds order antiferromagnetically at 6.2 K $(DyCu_2Ge_2),$ 5.6 K $(HoCu_2Ge_2),$ 3.0 K $(ErCu_2Ge_2),$ and 3.9 K $(TmCu_2Ge_2),$ and some of them exhibit additional magnetic transitions in the ordered state. In an external magnetic field the low-temperature specific heat changes significantly, which can be attributed to metamagnetic-like transitions. In this temperature region, the investigated samples show distinctly different magnetocaloric effect.
Źródło:
Acta Physica Polonica A; 2012, 122, 2; 391-393
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ordered Nanoporous Silica Modified with Nanoparticles of Lanthanide Oxides
Autorzy:
Zeleňáková, A.
Kapusta, O.
Zeleňák, V.
Powiązania:
https://bibliotekanauki.pl/articles/1368473.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.Fk
81.05.Rm
75.40.Cx
Opis:
Lanthanide oxide nanoparticles were encapsulated inside of pores of highly ordered periodic silica of SBA15 type with hexagonal symmetry. The magnetic properties of such nanoperticles were investigated. The structural characterization using the SAXS, XANES, XRD, and $N_{2}$ adsorption measurements showed the presence of lanthanide oxides of $Ln_{2}O_{3}$ type (Ln=La, Pr, Nd, Gd, Eu), with the size of about 5 nm, incorporated in nanoporous channel system. Their magnetic properties, studied by SQUID apparatus, showed the weak antiferromagnetic ordering at 2 K in the nanocomposites $Gd_{2}O_{3}$@SBA15, $Pr_{2}O_{3}$@SBA15 and $Nd_{2}O_{3}$@SBA15. This behaviour of the nanoparticles is caused by blocking process of magnetic moments, which at 300 K exhibit the superparamagnetism, evidenced from ZFC/FC magnetization.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 218-219
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
AC Magnetic Susceptibility Study of Fe and Co Based Nanoparticles
Autorzy:
Zeleňáková, A.
Kováč, J.
Zeleňák, V.
Powiązania:
https://bibliotekanauki.pl/articles/1368479.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.Fk
81.05.Rm
75.40.Cx
Opis:
We have investigated magnetic properties of three different samples composed of magnetic Fe or Co core and protective Au or Pt metallic shell, namely Fe@Au, Co@Au and Fe@Pt samples, with sizes of about 10 nm, 8 nm and 5 nm respectively. We have measured and analysed the experimental data of real and imaginary component of ac susceptibility through theoretical laws for non-interacting and interacting particles and we have estimated the strength of their magnetic interactions. Our analyses showed the increase of inter-particle interactions with decreasing particles size.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 222-223
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ti-Induced Ferromagnetism and the Specific Heat of $CaTi_xRu_{1-x}O_3$ (x=0, 0.005, 0.03)
Autorzy:
Zorkovská, A.
Baran, A.
Kajňaková, M.
Feher, A.
Šebek, J.
Šantavá, E.
Bradarić, I.
Powiązania:
https://bibliotekanauki.pl/articles/1813685.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Pq
75.40.Cx
72.80.Ga
Opis:
The influence of Ti substitution on the specific heat of the $CaTi_xRu_{1-x}O_3$ system at low concentrations x=0, 0.005, and 0.03 was studied in the temperature range of 2-300 K at magnetic fields up to 9 T. Small peak was revealed in the C/T vs. $T^2$ dependence at around 3 K, which are field sensitive (the electronic specific heat coefficient γlinearly decreases with the increase in magnetic field), and might be connected to some kind of magnetic ordering. The coefficient γis suppressed also by Ti substitution.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 355-358
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$[Ni(en)(H_2O)_4][SO_4] \cdot 2H_2O$ - an S = 1 Molecular Magnet with Easy-Plane Anisotropy
Autorzy:
Tarasenko, R.
Orendáčová, A.
Tibenská, K.
Potočňák, I.
Kajňaková, M.
Vlček, A.
Orendáč, M.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813818.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Et
75.30.Gw
75.40.Cx
Opis:
Structural analysis of $[Ni(en)(H_2O)_4][SO_4] \cdot 2H_2O$ was performed and it suggests that the crystal field should play a dominant role in the magnetic properties of the system. This conjecture coincides well with the specific heat and susceptibility behaviour. The analysis confirmed that the compound can be treated as a spin 1 single molecule magnet with nonmagnetic ground state introduced by easy-plane single-ion anisotropy D/$k_B$≈11 K and neglecting in-plane anisotropy E/D <0.1.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 481-484
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:
Structure and Magnetic Properties of Three-Dimensional Gadolinium-Based Hybrid Framework
Autorzy:
Almáši, M.
Zeleňáková, A.
Císařová, I.
Bednarčík, J.
Zeleňák, V.
Powiązania:
https://bibliotekanauki.pl/articles/1371241.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.Fk
81.05.Rm
75.40.Cx
Opis:
In the present work we have focused on the preparation and magnetic study of coordination polymer formed by Gd(III) cations as nodes and formate (HCOO¯; FOR) anions as charge compensating linkers. The prepared complex with formula ${[Gd(μ_{3}-FOR)_{3}]}_{n}$ was characterized by single-crystal X-ray diffraction, and high-energy powder X-ray diffraction. The structural study showed that complex is formed by 3D polymeric network with the shortest Gd-Gd, distances of 3.998 Å. The magnetic properties of the complex were studied by magnetic susceptibility $χ_{M}(T)$ and magnetization M(H) measurements. The results show on the weak antiferromagnetic coupling at low temperatures represented by the Weiss constant θ=-0.468 K. The value of effective magnetic moment $μ_{eff}=7.57μ_{B}$, which was estimated from the experimental data is close to the theoretical value for systems with S=7/2. Correlation between crystal structure of complexes and magnetic properties is presented.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 308-309
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Elastic Collision of Two H-Like Atoms Including the Exotic Ps and Mu
Autorzy:
Ray, H.
Powiązania:
https://bibliotekanauki.pl/articles/1030031.pdf
Data publikacji:
2017-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
36.10.Dr
03.65.Nk
34.50.Cx
Opis:
Elastic collision between two H-like atoms using the ab initio static-exchange model (SEM) and a modified static-exchange model (MSEM) at cold energies are investigated in the center of mass frame considering the system as a four-body Coulomb problem where all the Coulomb interaction terms in the direct and exchange channels are treated exactly. The importance of an exact calculation to find basic physics is highlighted. In addition, the dependence of scattering length on the van der Waals interaction between the atoms and the dependence of scattering length on reduced-mass of the system are derived which is completely new information in the field of science.
Źródło:
Acta Physica Polonica A; 2017, 132, 5; 1473-1477
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of 1D Ordering on Magnetic Properties of Iron Nanoparticles coated by Silica Shell
Autorzy:
Zeleňáková, A.
Hrubovčák, P.
Zeleňák, V.
Kováč, J.
Powiązania:
https://bibliotekanauki.pl/articles/1030766.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.75.Fk
68.37.Og
Opis:
Peculiar magnetic properties of 1D arranged composite consisting of Fe nanoparticles coated by insulating SiO2 layer were studied. Silica layer promotes the self-organization of 4 nm iron nanoparticles to the chain-like structures. Magnetization study shows that prepared nanoparticles exhibit very strong inter-particle magnetic interactions, which lead to long-range ordering of nanoparticles magnetic moments. Magnetic properties show superferromagnetic behaviour. The low value of room temperature coercivity, the existence of electrical insulating silica layer and small size of iron nanoparticles favour studied material for potential usage in microelectronic devices designed for high voltage signals modulated by high frequencies.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 561-563
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Behavior near the Ferromagnetic to Paramagnetic Phase Transition in Y₈Co₆₂B₃₀ Amorphous Alloy
Autorzy:
Śniadecki, Z.
Marcin, J.
Idzikowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/1031033.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.50.Kj
75.30.Sg
Opis:
The Y₈Co₆₂B₃₀ amorphous alloy is a collinear ferromagnet. The Arrott plot, the Kouvel-Fisher method, critical isotherm analysis and magnetic field dependence of maximum magnetic entropy changes were the main analytical tools used to determine the nature of the ferromagnetic/paramagnetic phase transition. Values of critical exponents (β, γ, and δ) were calculated and were convergent with those characteristic for mean-field model. It suggests that long range ferromagnetic interactions are playing main role in investigated alloy and the phase transition was confirmed to be of a second order according to the Banerjee criterion.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 967-969
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:
Invasive Cx43high sub-line of human prostate DU145 cells displays increased nanomechanical deformability
Autorzy:
Piwowarczyk, Katarzyna
Sarna, Michał
Ryszawy, Damian
Czyż, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/1038583.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
prostate cancer invasion
Cx43
cell elasticity
motility
AFM
Opis:
Connexin(Cx)43high cells are preferentially recruited to the invasive front of prostate cancer in vitro and in vivo. To address the involvement of Cx43 in the regulation of human prostate cancer DU145 cell invasiveness, we have analysed the nanoelasticity of invasive Cx43high sub-sets of DU145 cells by atomic force microscopy (AFM). The Cx43high DU145 cells displayed considerably higher susceptibility to mechanical distortions than the wild type DU145 cells. Transient Cx43 silencing had no effect on their elastic properties. Our data confirm the relationship between the invasive potential, Cx43 expression and nanoelasticity of the DU145 cells. However, they also show that Cx43 is not directly involved in the maintenance of DU145 invasive phenotype.
Źródło:
Acta Biochimica Polonica; 2017, 64, 3; 445-449
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Phase Transition in $CePd_{2}P_{2}$
Autorzy:
Tran, V.
Bukowski, Z.
Tran, L.
Zaleski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1371474.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.40.Gb
71.27.+a
Opis:
The tetragonal $CePd_{2}P_{2}$ compound has been investigated by ac magnetic susceptibility and dc magnetization measurements. The experimental data reveal a ferromagnetic phase transition at $T_{C}$=28.4± 0.2 K. Using Arrot-Noakes plot and scaling laws for a second-order phase transition, critical exponents for the ferromagnetic transition in the system were obtained. The critical exponents are located between those of the mean field and Heisenberg model values.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 334-335
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermodynamic and Magnetotransport Properties of High Quality $Na_{0.77}CoO_{2}$ Single Crystals
Autorzy:
Baran, A.
Zorkovská, A.
Kajňaková, M.
Lin, C.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1371577.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
75.40.Cx
75.47.-m
Opis:
Heat capacity and electrical resistivity of high-quality $Na_{0.77}CoO_{2}$ single crystals was systematically studied as a function of temperature and magnetic field. Anomalies at 20 K have been observed both in the heat capacity and the electrical resistivity. The broad bump in the heat capacity indicates a smeared magnetic phase transition. Magnetic fields up to 9 T, oriented perpendicularly to the ab plane, reduce the temperature of this anomaly in accordance with the assumption of A-type antiferromagnetic ordering. The low temperature upturn observed in resistivity below 20 K for slow cooling is also suppressed by the magnetic field. This anomaly is probably the consequence of the interplay of several different mechanisms, including the Kondo effect, electron-electron interactions, and electron-phonon scattering.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 360-361
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Behaviour of the Mean-Field Ferromagnet $Cu_{1.02}[Cr_{1.77}Ti_{0.24}]Se_4$
Autorzy:
Krok-Kowalski, J.
Władarz, G.
Rduch, P.
Malicka, E.
Groń, T.
Guzik, A.
Powiązania:
https://bibliotekanauki.pl/articles/1409626.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.50.Dd
64.60.Ht
Opis:
Magnetization, M, and susceptibility, χ, measurements showed both strong lowering of magnetic moment in comparison with $CuCr_2Se_4$ matrix and zero-field-cooling-field-cooling susceptibility splitting characteristic for the spin-glass behaviour. Isothermal magnetization curves, M(H), easy saturate and large values both of the Curie $T_{C}$=253 K and Curie-Weiss θ=283.5 K temperatures indicate the ferromagnetic order which coexists with the spin-glass state. The critical behaviour investigated around the paramagnetic-ferromagnetic phase transition revealed that the values of critical exponents are close to those predicted by the mean field model for long-range magnetic interactions.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1102-1104
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of $TbFe_{0.25}Ge_2,$ $TbSn_{0.4}Ge_{1.4}$ and $NdSn_{0.6}Ge_{1.775}$ Compounds
Autorzy:
Gil, A.
Duraj, R.
Szytuła, A.
Powiązania:
https://bibliotekanauki.pl/articles/1419610.pdf
Data publikacji:
2012-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.40.Cx
75.47.Np
Opis:
The magnetic data of $TbFe_{0.25}Ge_2,$ $TbSn_{0.4}Ge_{1.4}$ and $NdSn_{0.6}Ge_{1.775}$ compounds are reported. These compounds crystallize in the orthorhombic crystal structures described by the space group Cmcm (No. 63) and they are antiferromagnets with the Néel temperatures equal to 19.5, 22 and 3.7 K, respectively.
Źródło:
Acta Physica Polonica A; 2012, 122, 2; 394-395
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Griffiths-Like Phase in Nanocrystalline Manganite $La_{0.85}Ca_{0.15}MnO_3$
Autorzy:
Pękała, M.
Pękała, K.
Szydłowska, J.
Drozd, V.
Powiązania:
https://bibliotekanauki.pl/articles/1398277.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
75.40.Cx
76.30.-v
Opis:
The ferromagnetic Curie temperatures $T_{C}$ derived from a temperature derivative of AC susceptibility are equal to 106 K and 161 K for the nanocrystalline and polycrystalline manganites, respectively. The magnetic susceptibility and electron spin resonance confirm that the Griffiths-like phase exists above the Curie temperature in paramagnetic matrix of the nanocrystalline manganite. An analysis of electron spin resonance spectra allows to detect the upper temperature limit for an existence of Griffiths-like phase at temperature $T_{GI}=290 K$, which is somewhat higher than the $T_{G}$ of the magnetic susceptibility.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 774-776
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:
Chemical Potential Evidence for Phase Transitions in Magnetic and Superconducting Compounds and Alloys
Autorzy:
Matlak, M.
Pietruszka, M.
Powiązania:
https://bibliotekanauki.pl/articles/2012914.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
75.30.Kz
75.40.Cx
Opis:
We announce that all phase transitions (induced by temperature or concentration) including structural ones and transitions between metastable or "exotic" states can be detected by the chemical potential critical behaviour, as well as, from the average occupation numbers of the electronic system (critical electron redistribution).
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 253-256
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemical Potential as a Detector of Phase Transitions in Solids
Autorzy:
Matlak, M.
Gosławska, E.
Grabiec, B.
Eid, Kh.
Powiązania:
https://bibliotekanauki.pl/articles/2012963.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
75.30.Kz
75.40.Cx
Opis:
We show that the chemical potential exhibits small but distinct kinks at all critical temperatures as the evidence for phase transitions in the electronic system, structural phase transitions included. In the case of, at least, two kinds of interacting electrons average occupation numbers exhibit the same behavior.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 365-368
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:
KEr(MoO$\text{}_{4}$)$\text{}_{2}$ and CsDy(MoO$\text{}_{4}$)$\text{}_{2}$ - Low-Dimensional Ising Magnets
Autorzy:
Kačmár, M.
Orendáčová, A.
Čizmár, E.
Horváth, D.
Orendáč, M.
Bondarenko, V.
Anders, A. G.
Feher, A.
Jaščur, M.
Powiązania:
https://bibliotekanauki.pl/articles/2013657.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.10.Hk
75.40.Mg
Opis:
In the present work the behaviour of cluster excitations in magnetic field, B, parallel to the easy axis was experimentally studied by the measurements of KEr(MoO$\text{}_{4}$)$\text{}_{2}$ and CsDy(MoO$\text{}_{4}$)$\text{}_{2}$ specific heat, C, vs. B dependence studied at a constant temperature. Corresponding Monte Carlo simulations of C revealed that despite of the fact that the Ising exchange-coupling models proved useful for a sufficient description of the specific heat of these dipolar systems in B=0, the analysis of current experimental data requires a partial renormalization of exchange-coupling constants previously obtained from B=0 analysis. The influence of crystal field effects and long-range character of spin correlations is discussed.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 807-810
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Susceptibility Behaviour of CuGeO$\text{}_{3}$: Comparison between Experiment and the Quantum Transfer Matrix Approach
Autorzy:
Bieliński, M.
Renard, J.-P.
Powiązania:
https://bibliotekanauki.pl/articles/2013702.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.40.Cx
75.40.Mg
Opis:
Thermodynamical properties of one-dimensional S=1/2 Heisenberg model with dimerized nearest- and uniform next-nearest-neighbour interactions are studied by the numerically exact quantum transfer matrix method and the results are applied to CuGeO$\text{}_{3}$. Suzuki-Trotter formula is used to obtain a classical system with spin σ=3/2 and effective interactions between nearest-neigbours only. Magnetic susceptibility curve is calculated and compared with new experimental results performed in a wide temperature range, revealing the presence of frustration in the model proposed for CuGeO$\text{}_{3}$.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 851-854
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Numerically Generated Series Expansions for Spin-Lattice Systems
Autorzy:
Musiał, G.
Powiązania:
https://bibliotekanauki.pl/articles/2013729.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.60.-x
75.10.Hk
75.40.Cx
Opis:
The numerically generated series expansions complementary to widely used computer simulations of the Monte Carlo type, are presented. The effective algorithm for generation of graphs, which constitute the basis of series expansions for spin-lattice systems, is introduced. The use of the numerically generated series expansions to calculate the free energy for the eight-vertex model is explained and discussed in detail.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 901-904
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transfer-Matrix Simulations of Linear Magnetic Systems
Autorzy:
Matysiak, R.
Caramico D'Auria, A.
Esposito, F.
Esposito, U.
Powiązania:
https://bibliotekanauki.pl/articles/2013975.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.40.Cx
75.40.Mg
Opis:
The quantum transfer-matrix method was applied to study the finite-temperature static properties of the spin S=1 antiferromagnetic Heisenberg chains in a wide range of the single-ion anisotropy and temperatures. The high-resolution quantum transfer-matrix simulation data are obtained for the zero-field susceptibility, specific heat as well as for the field-dependent magnetization. The microscopic parameters of a number of real quasi-one-dimensional compounds are found from fitting procedures, some theoretical approaches are numerically verified and an extension of the technique to a non-uniform bond alternating molecular magnets is also put forward.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 959-962
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Mesoscopic Rings: Exact Simulations and Experiment
Autorzy:
Kamieniarz, G.
Matysiak, R.
Caramico D'Auria, A.
Esposito, F.
Benelli, C.
Powiązania:
https://bibliotekanauki.pl/articles/2014557.pdf
Data publikacji:
2000-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Mg
75.40.Cx
75.10.Jm
Opis:
A numerical transfer-matrix approach and an exact diagonalization technique exploiting the point-group symmetry are worked out in the framework of quantum statistical mechanics and group theory for finite rings. They are applied to spin models of the high nuclearity cyclic clusters [Mn(hfac)$\text{}_{2}$NITPh]$\text{}_{6}$ and Ni$\text{}_{12}$(O$\text{}_{2}$CMe)$\text{}_{12}$(chp)$\text{}_{12}$(H$\text{}_{2}$O)$\text{}_{6}$(THF)$\text{}_{6}$. The microscopic parameters of both molecules (J/k$\text{}_{B}$=350±10 K and J/k$\text{}_{B}$=8.5 K±0.5, g=2.23±0.01, respectively) are then obtained from a fit of the theoretical susceptibility curves to the experimental results which are supplemented for Ni$\text{}_{12}$ by new low-temperature measurements.
Źródło:
Acta Physica Polonica A; 2000, 98, 6; 721-727
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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