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Tytuł:
Phase Diagram of Spin-Orbital Model
Autorzy:
Oleś, A. M.
Feiner, L. F.
Zaanen, J.
Powiązania:
https://bibliotekanauki.pl/articles/1964677.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
75.30.Et
75.40.-s
75.10.Jm
Opis:
We show that the mean-field phase diagram of the realistic spin-orbital model derived for a perovskite lattice in three dimensions consists of four different classical magnetic phases which become degenerate at orbital degeneracy. The quantum fluctuations are drastically enhanced and suppress the classical long-range order, providing a new mechanism to stabilize a quantum spin liquid near the multicritical point.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 367-370
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Strongly Correlated Electron Behaviour in $CeT_2Al_8$ (T~=~Fe,~Co)
Autorzy:
Ghosh, S.
Strydom, A.
Powiązania:
https://bibliotekanauki.pl/articles/1427072.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
71.27.+a
75.30.Mb
75.20.Hr
Opis:
We report on studies of physical properties of the two compounds $CeFe_2Al_8$ and $CeCo_2Al_8$ in which we have found varying degrees of electronic correlational phenomena. No magnetic ordering was detected down to 0.4 K in either of the two compounds. At elevated temperatures an incoherent Kondo interaction between the Ce 4f-electron and the conduction electrons is prevalent in both compounds. $CeCo_2Al_8$ exhibits a stable 4f-electron magnetic moment, but in $CeFe_2Al_8$ an intermediate-valent state prevails near room temperature that eventually transforms into a Fermi-liquid ground state. The low-temperature specific heat of $CeCo_2Al_8$ shows typical strongly correlated electron behaviour and a - logT upturn in its electronic specific heat below about 10 K.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1082-1084
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-Fermi-Liquid State in $URu_{0.68}Pd_{0.32}Ge$
Autorzy:
Tran, V.
Gralak, D.
Powiązania:
https://bibliotekanauki.pl/articles/1385459.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
75.30.Mb
75.40.Cx
75.45.+j
Opis:
We report the measurements of dc-magnetization (M), specific heat $(C_{p})$ and electrical resistivity (ρ) of an intermetallic $URu_{0.68}Pd_{0.32}Ge$, that lies at the border between nonmagnetic and magnetic regimes in the magnetic phase diagram of solid solutions $URu_{1-x}Pd_{x}Ge$. The studied composition shows enhanced dc-magnetic susceptibility χ(T) and the Sommerfeld ratio $C_{p}(T)$/T at low temperatures. Below 4 K χ(T), $C_{p}(T)$/T and ρ(T) can be described by χ(T) ∝ $T^{-0.48}$, $C_{p}(T)$/T ∝ √T and ρ(T) ∝ c ln(T)+$AT^{3/2}$, respectively. These observations provide an evidence that $URu_{0.68}Pd_{0.32}Ge$ is a moderately heavy-fermion system with an electronic ground state of non-Fermi liquid character. We found non-linear effect of the magnetization and a large value of the Wilson ratio, which are consistent with the interpretation in terms of magnetic instability.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 312-314
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Strong Electronic Correlations in a New Yb-Based Compound: $YbCu_4Ni$
Autorzy:
Čurlik, I.
Reiffers, M.
Giovannini, M.
Gažo, E.
Šebek, J.
Šantavá, E.
Powiązania:
https://bibliotekanauki.pl/articles/1534605.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
75.30.-m
75.30.Mb
Opis:
Heat capacity measurements performed on the new ternary compound $YbCu_4Ni$ indicate for this compound strong electronic correlations with possible antiferromagnetic phase transition below 0.5 K. Susceptibility and magnetisation measurements above 2 K show no magnetic ordering.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 919-921
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
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:
Magnetic and Heat Capacity Study of the new $Gd_{1-x}Ce_xNi_5$ Series
Autorzy:
Dzubinska, A.
Reiffers, M.
Espeso, J.
Rodríguez Fernández, J.
Powiązania:
https://bibliotekanauki.pl/articles/1398287.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
75.30.-m
75.30.Mb
Opis:
We have prepared a new system of $Gd_{1-x}Ce_xNi_5$ polycrystalline samples with concentrations x =0, 0.2, 0.5, and 0.8 in order to study the influence of different rare-earths substitutions on the ground state connected with spin fluctuations. GdNi₅ is a ferromagnetic compound with $T_{C}=31.8 K$ and CeNi₅ is a well-known spin fluctuation compound without magnetic ordering down to the lowest temperatures. X-ray diffraction study confirms the hexagonal crystal structure and the single phase samples. Magnetic properties (M(T),M(B)) show that an increasing content of Ce depresses the transition temperature, $T_{C}$, down to 4.9 K for x=0.8. The heat capacity measurements confirmed these results.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 997-999
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of Magnetic Contribution to the Heat Capacity of $YbCu_4Ni$
Autorzy:
Čurlik, I.
Reiffers, M.
Giovannini, M.
Powiązania:
https://bibliotekanauki.pl/articles/1419635.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
75.30.-m
75.30.Mb
Opis:
An investigation of the magnetic heat capacity of the heavy-fermion compound $YbCu_4Ni$ up to 0.4 K is presented. The novel compound $LuCu_4Ni,$ isotypic with $YbCu_4Ni$ has been synthesized and characterized, and its heat capacity was measured in order to subtract the lattice contribution from the previously measured heat capacity data of $YbCu_4Ni$.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 3-5
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport and Magnetic Properties of $YbCu_4Ni$
Autorzy:
Čurlik, I.
Mát'ošová, Š.
Il'kovič, S.
Reiffers, M.
Giovannini, M.
Powiązania:
https://bibliotekanauki.pl/articles/1419636.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
75.30.-m
75.30.Mb
Opis:
The results on the influence of magnetic field on the electrical resistivity ρ(T) of the heavy fermion $YbCu_4Ni$ in the temperature range 0.4-300 K are presented. We have observed a Kondo-like behaviour below 10 K with a minimum in ρ(T) at about 60 K. An applied magnetic field depresses this behaviour, and a maximum in ρ(T) appears similarly to the maximum observed in heat capacity. The observed electrical magnetoresistance shows negative values in all applied magnetic fields and with increasing temperature its absolute magnitude increases. Moreover, we extended our previous susceptibility measurements up to high temperatures of 1000 K, in order to study possible mixed valence behaviour, which however was not observed.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 6-10
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of NpPdSn
Autorzy:
Gofryk, K.
Griveau, J.
Jardin, R.
Colineau, E.
Rebizant, J.
Wastin, F.
Caciuffo, R.
Powiązania:
https://bibliotekanauki.pl/articles/1810298.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
71.27.+a
75.30.Mb
Opis:
A new compound NpPdSn was prepared and studied by X-ray diffraction, magnetization, heat capacity and electrical resistivity measurements, performed in the temperature range 2-300 K and under magnetic field up to 14 T. The crystal structure determined by single-crystal X-ray analysis is hexagonal with ZrNiAl-type (space group $P\bar{6}2m$). NpPdSn orders antiferromagnetically at 19 K and exhibits a Curie-Weiss behavior with $μ_\text{eff}=2.66 μ_{B}$ and $Θp_{p}$=-47 K. Bulk properties show temperature variations similar to systems with strong electronic correlations with a large negative paramagnetic Curie temperature and an enhanced low-temperature specific heat (γ≈90 mJ/(mol $K^{2}$)). It suggests that NpPdSn may be classified as a new Np-based antiferromagnetic Kondo lattice, one of the very few known amidst transuranium-based intermetallics.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 80-82
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Excitations in Doped Manganites
Autorzy:
Oleś, A. M.
Feiner, L. F.
Powiązania:
https://bibliotekanauki.pl/articles/2012881.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Ds
75.30.Et
71.27.+a
Opis:
We generalize the double exchange to describe holes doped in degenerate e$\text{}_{g}$ orbitals in La$\text{}_{1-x}$A$\text{}_{x}$MnO$\text{}_{3}$ manganites, where A are divalent alkaline earth ions. Assuming an orbital liquid of disordered e$\text{}_{g}$ orbitals we find isotropic ferromagnetic exchange interactions which increase with hole doping. The magnon dispersion agrees very well with the experimental data in ferromagnetic metallic manganites.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 193-196
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crystal Structure and Magnetic Properties of new Eu-Pd-Sn Compounds
Autorzy:
Čurlík, I.
Gastaldo, F.
Giovannini, M.
Strydom, A.
Reiffers, M.
Powiązania:
https://bibliotekanauki.pl/articles/1032628.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
75.30.Mb
75.30.-m
Opis:
We report on the synthesis, crystal structure determination, and magnetic susceptibility measurements of Eu₃Pd₂Sn₂, EuPd₂Sn₄, and EuPdSn₂. For all three compounds a divalent state of Eu ions was obtained from the fitting of the magnetic susceptibilities. At low temperatures Eu₃Pd₂Sn₂, EuPd₂Sn₄, and EuPdSn₂ order magnetically at 23, 12, and 13 K, respectively.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1003-1005
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Point Contact Properties of $R_3Pd_{20}X_6$ (R = La, Ce; X = Si, Ge) Cage Compounds
Autorzy:
Čurlik, I.
Strydom, A.
Reiffers, M.
Powiązania:
https://bibliotekanauki.pl/articles/1534404.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
75.30.-m
75.30.Mb
Opis:
Point-contact spectroscopy measurements have been performed on the $R_3Pd_{20}X_6$ (R = La, Ce; X = Si, Ge) cage compounds. In case of La the characteristic phonon energies have been obtained in agreement with that of the Raman scattering. In $Ce_3Pd_{20}Si_6$ we have observed asymmetric behaviour of dV/dI(V) dependences which was observed in non-Fermi liquid compound. In $Ce_3Pd_{20}Ge_6$ we have observed maxima at crystalline electric field energies, influenced by magnetic field. This is connected with quadrupolar ordering transition.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 907-909
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kondo Lattice Models for Rare-Earth and Actinide Systems
Autorzy:
Coqblin, B.
Powiązania:
https://bibliotekanauki.pl/articles/1426694.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
75.10.Nr
75.30.Nr
Opis:
We present here some works on the strong competition between the Kondo effect, magnetic order and eventually spin glass or frustration effect in anomalous rare-earth and actinide systems. First, we develop an underscreened Kondo lattice model with $S_{f}$ = 1 spins for the 5f-electrons and we have recently improved it by deriving, by the Schrieffer-Wolff transformation, a 5f-band with a finite bandwidth. The underscreened Kondo lattice model can account for properties of some uranium and neptunium compounds, like UTe, $Np_2PdGa_3$ or $UCu_2Si_2$ which have a large Curie temperature $T_{c}$ of order 100 K and present also a Kondo behavior. In particular, we can account for the observed maximum of $T_{c}$ under pressure in UTe and the magnetization curves of $NpNiSi_2$ showing the occurrence of the Kondo effect at low temperatures below $T_{c}$. Second, we have studied the properties of disordered cerium alloys like $CeCu_xNi_{1-x}$ or $CeRh_xPd_{1-x}$ by considering the Kondo effect, a ferromagnetic order and a spin glass behavior described by several approaches. The van Hemmen approach gives a good explanation of the properties of cerium alloys and we are describing the magnetic glass clusters which occur in both spin glass and ferromagnetic phases. Third, we present a new description of a frustrated Kondo lattice model, which can account for the behavior under pressure or doping of some ytterbium compounds like $Yb_2Pd_2Sn$ and YbAgGe.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1005-1013
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exact Diagonalization Study of an Extended Hubbard Model for a Cubic Cluster at Quarter Filling
Autorzy:
Szałowski, K.
Balcerzak, T.
Jaščur, M.
Bobák, A.
Žukovič, M.
Powiązania:
https://bibliotekanauki.pl/articles/1032794.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.75.-c
75.10.Lp
71.27.+a
65.80.-g
05.70.Ce
Opis:
In the paper the thermodynamics of a cubic cluster with 8 sites at quarter filling is characterized by means of exact diagonalization technique. Particular emphasis is put on the behaviour of such response functions as specific heat and magnetic susceptibility. The system is modelled with extended Hubbard model which includes electron hopping between both first and second nearest neighbours as well as Coulombic interactions, both on-site and between nearest-neighbour sites. The importance of hopping between second nearest neighbours and Coulombic interactions between nearest neighbours for the temperature dependences of thermodynamic response functions is analysed. In particular, the predictions of the Schottky model are compared with the calculations based on the full energy spectrum.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1012-1014
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metals and Semimetals with Strongly Correlated Electrons
Autorzy:
Fulde, P.
Powiązania:
https://bibliotekanauki.pl/articles/1953157.pdf
Data publikacji:
1997-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
71.27.+a
71.10.Fd
75.30.Mb
Opis:
A characteristic feature of strongly correlated electrons is the appearance of low energy scales. They may result in heavy-quasiparticle excitations at low temperatures. Our understanding of these excitations has been considerably modified over the last few years. While it was originally thought that the Kondo effect is the sole source of heavy-fermion behavior, two additional mechanisms have been identified meanwhile. One is based on the Zeeman effect and occurs in Nd$\text{}_{2-x}$Ce$\text{}_{x}$CuO$\text{}_{4}$. The other is operative in the semimetal Yb$\text{}_{4}$As$\text{}_{3}$ and is based on nearly half filled one-dimensional Hubbard chains. In all three cases the low energy excitations result from spin degrees of freedom.
Źródło:
Acta Physica Polonica A; 1997, 91, 1; 67-76
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 44

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