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Tytuł:
Magnetic Susceptibility of HgTe⟨Mn,Fe,Cr⟩
Autorzy:
Frasunyak, V. M.
Gavaleshko, M. P.
Powiązania:
https://bibliotekanauki.pl/articles/1933741.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
Opis:
The results of the investigations of magnetic susceptibility (χ) of HgTe⟨Mn,Fe,Cr⟩ with N$\text{}_{3d}$ < 10$\text{}^{21}$ cm$\text{}^{-3}$ in temperature range of 80-290 K and for magnetic fields of 0.4-9 kOe are presented. It was shown that χ$\text{}_{Mn}$(T) and χ$\text{}_{Fe}$(T) in HgTe⟨Mn,Fe⟩ are described by Curie law and for Ν$\text{}_{3d}$ > 10$\text{}^{21}$ cm$\text{}^{-3}$ - by Curie-Weiss law with negative value of θ$\text{}_{p}$, characterizing the antiferromagnetic interaction between magnetic ions. Thermal treatment of HgTe⟨Fe⟩ samples in Hg vapour at Τ = 500 K in contrast to HgTe⟨Mn⟩ leads to the redistribution of magnetic component only in these samples. A special behaviour of χ(T) in HgTe⟨Cr⟩ samples was revealed which is different from x(T) in HgTe⟨Mn,Fe⟩.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 715-718
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Is the Magnetism of HgSe:Fe Clearly Understood?
Autorzy:
Dybko, K.
Łusakowski, A.
Kossut, J.
Arciszewska, M.
vd Linden, P. J. E. M.
Wittlin, A.
Perenboom, J. A. A. J.
Mycielski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1931952.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Hx
75.20.Hr
Opis:
The high magnetic field magnetization measurements of low composition Hg$\text{}_{1-x}$Fe$\text{}_{x}$Se (0.0002 < x < 0.003) at temperatures ranging from 1.6 K to 40 K and in magnetic fields up to 20 T are reported. The magnetization in a sample containing only Fe$\text{}^{3+}$ ions (x = 0.0002) is described by the Brillouin function (j = 5/2). The magnetization in the sample codoped with Ga, containing only Fe$\text{}^{2+}$ is well described in the model of isolated Fe$\text{}^{2+}$ ions. The latter model takes into account the tetrahedral crystal field, the spin-orbit interaction and the Zeeman term. On the other hand, the magnetization of sample with both Fe$\text{}^{3+}$ and Fe$\text{}^{2+}$ present simultaneously (x = 0.003) is shown to be different from a simple additive superposition of the contributions due to Fe$\text{}^{3+}$ and Fe$\text{}^{2+}$ subsystems. The possible origin of this discrepancy is discussed.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 193-196
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization of Pb$\text{}_{1-x}$Cr$\text{}_{x}$Te Semimagnetic Semiconductor
Autorzy:
Mac, W.
Story, T.
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1876309.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.20.Hr
Opis:
We present experimental studies of magnetization of Pb$\text{}_{1-x}$Cr$\text{}_{x}$Te (x ≤ 0.01) crystals. The reasonable description of the data is obtained for a composition of x ≤ 0.001 using Cr$\text{}^{+++}$ model (Brillouin type paramagnetism S = 3/2).
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 492-494
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Icosahedral (Au,Cu)-Al-Yb Quasicrystals
Autorzy:
Oki, S.
Hiroto, T.
Muro, Y.
Tamura, R.
Powiązania:
https://bibliotekanauki.pl/articles/1373451.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Kj
75.20.Hr
Opis:
We have synthesized Cu-substituted (Au,Cu)-Al-Yb quasicrystals in order to investigate the relationship between the quasilattice constant and the magnetic property. The quasilattice constant $a_{R}$ is found to decrease as Au is replaced by Cu, and the maximum reduction of 2.18% in $a_{R}$ was observed for x=0.60 in $(Au_{1-x}Cu_x)_{49}Al_{34}Yb_{17}$. Magnetic measurements of $(Au_{1-x}Cu_x)_{49}Al_{34}Yb_{17}$ (x=0, 0.10, 0.20, 0.50) show that the intermediate-valence state of Yb persists in all the studied compositions. The effective magnetic moment is found to depend on r̅/$a_{R}$ rather than on the quasilattice constant $a_{R}$. This suggests that r̅/$a_{R}$ can be regarded as a measure of the chemical pressure induced on the Yb atoms.
Źródło:
Acta Physica Polonica A; 2014, 126, 2; 553-555
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Behaviour in CeNiGa$\text{}_{2}$ and Ce$\text{}_{2}$Ni$\text{}_{2}$Ga
Autorzy:
Kaczorowski, D.
Rogl, P.
Powiązania:
https://bibliotekanauki.pl/articles/1964573.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
75.30.Mb
Opis:
The bulk properties of CeNiGa$\text{}_{2}$ and Ce$\text{}_{2}$Νi$\text{}_{2}$Ga were studied by means of magnetic susceptibility, magnetization and electrical resistivity measurements. It was found that CeNiGa$\text{}_{2}$ is an antiferromagnetically ordered dense Kondo system whereas Ce$\text{}_{2}$Ni$\text{}_{2}$Ga exhibits a fluctuating valence behaviour.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 289-293
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic and Magnetic Properties of $ThCo_4B$
Autorzy:
Szajek, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813651.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
75.20.Hr
Opis:
$ThCo_4B$ compound crystallizes in the hexagonal $CeCo_4B$ type structure. The electronic structure is calculated based on full-potential local-orbital full-relativistic method. The ab initio calculations showed that small magnetic moments (≈0.1 $μ_B$/atom) are formed on Th and B atoms, antiparallel to the moments on Co atoms equal to 1.55 and 0.43 $μ_B$/atom for Co(2c) and Co(6i), respectively. The densities of states at the Fermi level are equal to 1.3 and 5.4 states/(eV spin f.u.) for spin up and down, respectively. These values are predominated by Co(3d) electrons.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 283-286
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ab Initio Study of Electronic and Magnetic Structure and Structural Phase Transition of $(Fe_{1 - x}Mn_{x})_2P_{1 - y}Ge_{y}$ Alloys
Autorzy:
Deniszczyk, J.
Woźniakowski, A.
Kolano, R.
Kolano-Burian, A.
Powiązania:
https://bibliotekanauki.pl/articles/1427520.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Be
75.20.Hr
Opis:
The paper presents results of the ab initio electronic structure calculations performed for the $(Fe_{0.5}Mn_{0.5})_2P_{0.67}Ge_{0.33}$ alloy, a member of $(Fe_{1 - x}Mn_{x})_2P_{1 - y}Ge_{y}$ family of alloys showing a giant magnetocaloric effect. Calculations confirmed the strong relationship between the magnetic state and crystal structure of the alloy. To investigate the isostructural phase transition driven by external magnetic field observed in $(Fe_{0.9}Mn_{1.1})P_{0.8}Ge_{0.2}$ we utilized the fixed spin moment approach. Total energy analysis confirmed the occurrence of isostructural phase transition.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1162-1164
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Jahn-Teller Center as Quasiparticle of Fractional Statistics
Autorzy:
Sobolewski, A. I.
Powiązania:
https://bibliotekanauki.pl/articles/1933566.pdf
Data publikacji:
1995-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
31.10.+z
Opis:
Arguments are presented towards the identification of a molecular center undergoing a linear E⊗e Jahn-Teller effect as a quasiparticle of fractional statistics. The relevance of Jahn-Teller quasiparticles for the description of the type-II superconductivity is briefly discussed.
Źródło:
Acta Physica Polonica A; 1995, 88, 2; 305-313
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisotropy of Magnetic Interactions in HgFeSe
Autorzy:
Wilamowski, Z.
Przybylińska, H.
Joss, W.
Guillot, M.
Powiązania:
https://bibliotekanauki.pl/articles/1921599.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ey
75.20.Hr
Opis:
Magnetic properties (susceptibility, high-field torque and magnetization) of cubic HgFeSe are analyzed. Van Vleck magnetism of Fe$\text{}^{2+}$ is well evidenced. The energy splitting of the Fe levels in HgSe is shown to differ considerably from that in other II-VI compounds.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 689-692
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low Temperature Transport and Magnetic Properties of SmB$\text{}_{6}$
Autorzy:
Gabani, S.
Flachbart, K.
Pavlík, V.
Konovalova, E.
Paderno, Y.
Herrmannsdörfer, T.
Powiązania:
https://bibliotekanauki.pl/articles/2013029.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
71.28.+d
Opis:
We present results of transport and magnetic properties of three single-crystalline samples of the intermediate valence small-gap semiconductor SmB$\text{}_{6}$ at low temperatures. The received resistivity dependences of the samples below 0.5 K exhibit an activated behavior with an energy gap of a few mK. The temperature dependences of the magnetic susceptibility show an increase below 15 K which can be accounted for by impurities, by bare Sm$\text{}^{3+}$ ions or by a small amount of in-gap magnetic 4f$\text{}^{5}$5d$\text{}^{1}$ states.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 419-422
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Mott Transition in Disordered Systems
Autorzy:
Dobrosavljević, V.
Kotliar, G.
Powiązania:
https://bibliotekanauki.pl/articles/1860793.pdf
Data publikacji:
1994-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
71.55.Jv
Opis:
We review the recent progress in understanding the Mott transition in disordered systems using the mean-field approach to the strong correlation problem. It is based on a new functional integral formulation of the disordered interacting electron problem. The saddle-point solution recovers a mean-field theory of the strong correlation problem, and becomes exact in the limit of large spatial coordination. We compare the results of the mean-field theory with experimental findings and indicate directions for future work.
Źródło:
Acta Physica Polonica A; 1994, 85, 1; 21-38
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Importance of the Spin-Orbit Coupling for 3d-Ion Compounds: the Case of NiO
Autorzy:
Radwański, R. J.
Ropka, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2013984.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
71.70.Ej
Opis:
The orbital and spin moment of the Ni$\text{}^{2+}$ ion in NiO has been calculated at 0 K to be 0.54 μ$\text{}_{B}$ and 1.99 μ$\text{}_{B}$ respectively. Such large orbital moment, more than 20% of the total moment of 2.53 μ$\text{}_{B}$, proves the need for the "unquenching" of the orbital moment in compounds containing 3d ions. It turns out that the spin-orbit coupling is indispensable for description of magnetic and electronic properties of 3d-ion compounds.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 963-965
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:
Dynamic Crystal Field in CePb$\text{}_{3}$
Autorzy:
Lipiński, S.
Szajek, A.
Powiązania:
https://bibliotekanauki.pl/articles/2012928.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Dg
75.20.Hr
75.30.Mb
Opis:
The crystal field of valence fluctuating systems is time dependent due to f-electron transfers to the conduction band. We examine the effects of crystal field fluctuations on the neutron spectra, the specific heat and susceptibility of CePb$\text{}_{3}$.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 245-248
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisotropy of Susceptibility and Optical investigation of the Antiferromagnetic phase Transition in U$\text{}_{1-x}$Ce$\text{}_{x}$Ru$\text{}_{2}$Si$\text{}_{2}$
Autorzy:
Mihalik, M.
Maťaš, S.
Macko, D.
Timko, M.
Menovsky, A. A.
Powiązania:
https://bibliotekanauki.pl/articles/1955512.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Hb
75.20.Hr
72.15.-v
Opis:
Temperature dependence of magnetic susceptibility of U$\text{}_{1-x}$Ce$\text{}_{x}$Ru $\text{}_{2}$Si$\text{}_{2}$ single crystals (x=0, 0.025, 0.05, 0.075) has been studied at temperatures from 4.2 K up to room temperature and in magnetic fields applied along and perpendicular to the c-axis. The attention was paid to anomalies connected with the antiferromagnetic phase transition, which are present in crystals with x≤0.05. Far-infrared measurements of U$\text{}_{0.99}$Ce$\text{}_{0.01}$ Ru$\text{}_{2}$Si$\text{}_{2}$ single crystal have been studied for the first time. The measurements support the assumption that the origin of magnetic ordering in U$\text{}_{0.99}$Ce$\text{}_{0.01}$Ru$\text{}_{2}$Si$\text{}_{2}$ is the same as in heavy-fermion superconductor URu$\text{}_{2}$Si$\text{}_{2}$ and can be interpreted as being due to a spin-density-wave gap.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 351-354
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anomalous Transport and Thermal Properties of the Solid Solutions U$\text{}_{1-x}$Th$\text{}_{x}$Cu$\text{}_{5}$M (M = Al, Ga, In and Sn)
Autorzy:
Troć, R.
Tran, V. H.
Kaczorowski, D.
Czopnik, A.
Powiązania:
https://bibliotekanauki.pl/articles/2011211.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Mb
72.15.Qm
75.20.Hr
Opis:
UCu$\text{}_{5}$M-type compounds are moderate heavy fermion systems with an antiferromagnetic order below T$\text{}_{N}$ = 18, 16-25, and 25 K for M = Al, (Ga, In), and In, respectively, and a ferrimagnetic order with T$\text{}_{C}$ = 54 K for M = Sn. We present the results of magnetoresistance measurements as a function of temperature and applied magnetic field for the pure compounds and for their solid solutions containing Th, i.e. U$\text{}_{1-x}$Th$\text{}_{x}$Cu$\text{}_{5}$M. Only in the case of UCu$\text{}_{5}$In a substantial positive contribution to the magnetoresistance was observed at low temperatures, as for normal antiferromagnets. For the Al- and Sn-based alloys the magnetoresistance at low temperatures is negative, and its field variation proves the existence of Kondo-type interactions. On Th-substitution the magnetic phase transition is shifted to lower temperature and simultaneously the magnetoresistance becomes less negative. The field dependence of the magnetoresistance of these alloys can be well described by the Coqblin-Schrieffer model. Interestingly, the heat capacity measurements have revealed a general tendency to increase the linear coefficient γ with magnetic dilution of a given UCu$\text{}_{5}$M compound by Th-substitution. This feature reflects an enlargement of the effective mass of conduction electrons with the increase in both the unit cell volume and magnetic dilution. Such a tendency is also observed for the system UCu$\text{}_{5}$(In$\text{}_{1-x}$Ga$\text{}_{x}$), though the unit cell is here suppressed with increasing x. Thus, a similar physical picture is reached in all these systems but involving probably different mechanisms.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 25-35
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Substitution Study on the Coherent Kondo State in CeCu$\text{}_{5}$In
Autorzy:
Kaczorowski, D.
Kalychak, Ya. M.
Zaremba, V. I.
Powiązania:
https://bibliotekanauki.pl/articles/2012871.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Mb
72.15.Qm
75.20.Hr
Opis:
Ternary alloys CeCu$\text{}_{5-x}$In$\text{}_{1+x}$ were studied by means of magnetic and electrical resistivity measurements. In CeCu$\text{}_{5}$In a coherent Kondo state without long-range magnetic order develops at low temperatures. It transforms into an incoherent Kondo state upon small substitution of In for Cu.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 189-192
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two Kondo Impurities in Armchair Graphene Nanoribbon
Autorzy:
Lipiński, S.
Krychowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/1426905.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.Pr
75.20.Hr
75.30.Et
Opis:
An interplay of the Kondo effect and inter-impurity correlations in the armchair graphene nanoribbon is studied in the mean field slave boson approach. The effect of the hole doping is examined.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1063-1065
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Susceptibility Studies of Fe-Doped II-VI Compounds
Autorzy:
Arciszewska, M.
Powiązania:
https://bibliotekanauki.pl/articles/1886787.pdf
Data publikacji:
1991-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
72.80.Ey
75.30.Cr
Opis:
Low-field magnetic susceptibility χ of Fe-doped II-VI compounds has been studied for wide iron concentration range (3 x 10$\text{}^{18}$ ≤ N$\text{}_{Fe}$ ≤ 10$\text{}^{21}$ cm$\text{}^{-3}$). For the low iron content the Van Vleck-type paramagnetism is observed at low temperatures in all investigated materials (except for Hg$\text{}_{1-x}$Fe$\text{}_{x}$Se), which entirely confirms the theoretical prediction. For the higher Fe contents the experimental data still remain unexplained.
Źródło:
Acta Physica Polonica A; 1991, 79, 2-3; 341-344
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Susceptibility of Cd$\text{}_{1-x}$Fe$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$
Autorzy:
Arciszewska, M.
Mycielski, A.
Dobrowolski, W.
Lenard, A.
Mauger, A.
Witkowska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1890693.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ey
75.20.Hr
75.30.Cr
Opis:
Magnetic susceptibility of Cd$\text{}_{1-x}$Fe$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$ was found to consist of Van Vleck term (characteristic for the Fe$\text{}^{2+}$ centers in tetrahedral crystal symmetry) and temperature-dependent contribution. The occurrence of the latter indicates an existence of additional magnetic moments. We ascribe their origin to the modification of the Fe$\text{}^{2+}$ energy level spectrum induced by mixed Te-Se anion environment.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 303-306
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of $MeB_{50}$ (Me = 3d Atom) Compounds
Autorzy:
Panfilov, A.
Grechnev, G.
Filipov, V.
Lyashchenko, A.
Levchenko, G.
Powiązania:
https://bibliotekanauki.pl/articles/1372496.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
75.30.Hx
81.05.Je
Opis:
Temperature dependence of the static magnetic susceptibility for higher borides $MeB_{50}$, where Me = V, Cr, Mn, Fe, Co and Ni, was measured by Faraday method in the temperature range of 78-300 K. The value of effective magnetic moment of 3d-ions, resulted from the experiment, is compared with corresponding data of the ab initio calculations of the electronic structure and magnetic properties of these compounds based on the density functional theory.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 400-401
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ferromagnetism and Metal-Insulator Transitions in Correlated Electron Systems with Alloy Disorder
Autorzy:
Byczuk, K.
Yu, U.
Hofstetter, W.
Vollhardt, D.
Powiązania:
https://bibliotekanauki.pl/articles/1810278.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.23.-k
75.20.Hr
75.30.Mb
Opis:
Alloy disorder can affect ferromagnetism and metal-insulator transitions of correlated lattice fermion systems in subtle and often unexpected ways. Solving the Hubbard model and the periodic Anderson model within dynamical mean-field theory we show that alloy disorder can increase the Curie temperature of a non-disordered system, and also yields novel Mott or Kondo insulators at fractional electronic densities.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 7-12
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Behaviour of the Ce-Co-Mn Intermetallics of MgCu₂ Structure Type
Autorzy:
Dudric, R.
Popescu, A.
Isnard, O.
Pop, V.
Coldea, M.
Powiązania:
https://bibliotekanauki.pl/articles/1402321.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Eh
75.20.En
75.20.Hr
75.30.Cr
Opis:
The magnetic properties of CeCoMn, Ce₃Co₃Mn₄ and Ce₃Co₆Mn alloys have been investigated by magnetization and susceptibility measurements in the temperature range (5-300) K and magnetic field up to 12 T. X-ray powder diffraction measurements showed that all three alloys are isostructural and crystallize in the cubic MgCu₂ structure type. Both Ce and Co atoms are non-magnetic in all alloys like in the isostructural compound CeCo₂. Magnetic behavior of the investigated alloys is mostly due to the Mn moments and depends essentially on the Mn-Mn distances. The interaction between the Mn moments is antiferromagnetic in CeCoMn and Ce₃Co₃Mn₄ but a paramagnetic behavior for Ce₃Co₆Mn was evidenced in the studied temperature range.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 67-71
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mixed-Valence State in $Yb_2CuGe_6$
Autorzy:
Szytuła, A.
Penc, B.
Konyk, M.
Winiarski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813177.pdf
Data publikacji:
2008-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Lp
75.20.Hr
79.60.-i
Opis:
We present here temperature dependent X-ray photoemission measurements on polycrystalline $Yb_2CuGe_6$. The analysis of these data shows the change in the effective valence, determined directly from the 4f intensity ratio, as a function of temperature.
Źródło:
Acta Physica Polonica A; 2008, 113, 4; 1205-1209
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aspects of Magnetism in Heavy-Electron Metals
Autorzy:
Ott, H. R.
Powiązania:
https://bibliotekanauki.pl/articles/1860764.pdf
Data publikacji:
1994-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.-g
75.20.Hr
75.30.-m
75.30.Mb
Opis:
For some time it was believed that heavy-mass electrons at low temperatures, in special rare-earth and actinide compounds, were due to a particular suppression of magnetic order in these materials. Various experiments reveal, however, that magnetic order may occur from a heavy-electron state and that also a heavy-electron state may develop in the presence of a magnetically-ordered matrix. Even in materials with no sign of a cooperative phase transition, microscopic experimental probes give evidence for strong magnetic correlations, involving only very tiny (< 10^{-1} μ_{B}) ordered moments, however. All these experimental observations indicate that the heavy-electron state cannot always be regarded as a simple Fermi liquid in the usual sense. Various interactions of similar strength need to be considered. It is suggested that the balance of these interactions may lead to electronic inhomogeneities in k space. Both in magnetically-ordered or superconducting systems, unexpected electronic degrees of freedom appear to exist. In other cases experimental observations suggest magnetic inhomogeneities in real space which are not simply due to chemical inhomogeneities. Different examples of these various possibilities are demonstrated and discussed.
Źródło:
Acta Physica Polonica A; 1994, 85, 1; 7-19
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Magnetic Impurities in Gapless Fermi Systems
Autorzy:
Borkowski, L. S.
Powiązania:
https://bibliotekanauki.pl/articles/1955519.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Qm
75.20.Hr
74.70.Tx
Opis:
In ordinary metals, antiferromagnetic exchange between conduction electrons and a magnetic impurity leads to screening of the impurity spin below the Kondo temperature, T$\text{}_{K}$. In systems such as semimetals, small-gap semiconductors and unconventional superconductors, a reduction in available conduction states near the chemical potential can greatly depress T$\text{}_{K}$. The behavior of an Anderson impurity in a model with a power-law density of states, ρ(ε) ∝ |ε|$\text{}^{r}$, r>0, for |ε|<Δp, where Δp is small compared to the bandwidth, is studied using the non-crossing approximation. The transition from the Kondo singlet to the magnetic ground state can be seen in the behavior of the impurity magnetic susceptibility χ. The product Tχ saturates at a finite value at low temperature for coupling smaller than the critical one. For sufficiently large coupling Tχ → 0, as T → 0, indicating a complete screening of the impurity spin.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 359-362
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Seebeck Coefficient of CePd$\text{}_{3}$
Autorzy:
Mahan, G. D.
Bartkowiak, M.
Powiązania:
https://bibliotekanauki.pl/articles/2011215.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Jf
72.15.Qm
75.20.Hr
Opis:
Rare earth compounds have potential applications in thermoelectric devices due to their large value of conductivity and Seebeck coefficient. CePd$\text{}_{3}$ has the highest reported Seebeck coefficient (S ~ 125 μV/K), when doped appropriately, among all rare-earth compounds. This high value is explained as a result of the placement of the cerium f$\text{}^{1}$ level.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 37-42
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interplay of Kondo and Fano Resonance in Electronic Transport in Nanostructures
Autorzy:
Bułka, B. R.
Stefański, P.
Tagliacozzo, A.
Powiązania:
https://bibliotekanauki.pl/articles/2043700.pdf
Data publikacji:
2005-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.63.-b
72.15.Qm
75.20.Hr
Opis:
Quantum interference and electronic correlations are processes relevant for electronic transport in nanostructures. We present theoretical studies of transport for various models, which take into account these processes and describe the Fano resonance as well as many-body effects like the Kondo resonance. The results are compared with transport measurements performed on a small quantum dot strongly coupled to electrodes, a large semi-open quantum dot, a side-attached quantum dot to a quantum wire systems and a quantum dot embedded in the metallic ring. We show how conductance characteristics of the Kondo and the Fano resonance are modified in different situations.
Źródło:
Acta Physica Polonica A; 2005, 108, 4; 555-569
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectral Properties and New Interpolating Solution of Anderson Model
Autorzy:
Kuzemsky, A. L.
Powiązania:
https://bibliotekanauki.pl/articles/1964660.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
67.40.Db
71.28.+d
75.20.Hr
Opis:
A new approach to many-body quasiparticle dynamics of the Anderson impurity model at finite temperatures is proposed in the framework of the equation-of-motion method. We find a new exact identity, which relates the one-particle and many-particle Green functions. Using this identity, it is shown that a new interpolating approximation for the one-particle Green function can be constructed. The approximation which simultaneously reproduces the weak-coupling limit and the strong coupling limit can be formulated self-consistently. This approach offers a new method for a systematic construction of the approximate interpolating dynamical solutions of strongly correlated electron models.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 355-358
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Co substitution on Ni₂MnGe Heusler alloy: ab initio study
Autorzy:
Pugaczowa-Michalska, M.
Powiązania:
https://bibliotekanauki.pl/articles/1048335.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
71.23.-k
75.70.Ak
75.70.Cn
Opis:
Ab initio calculations shown that the Co substitution instead of Ni in Ni₂MnGe with the L2₁ crystallographic structure leads to a decrease of the lattice constant and an increase of the total magnetic moment of the Ni_{2-x}Co_{x}MnGe compounds. The Mn(B) has the largest local moment above 3 μ_{B} coupled parallel to moments on the Ni(A,C) and Co(A,C), which are found in the ranges of 0.19÷0.26 μ_{B} for Ni(A,C) and 1.03÷0.97 μ_{B} for Co(A,C) for studied range of x. Using the results stemming from the total energy calculations, the values of bulk modulus and its pressure derivatives are estimated according to the Murnaghan EOS.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 495-497
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:
Specific Heat of $YbNi_4Si$ Compound
Autorzy:
Falkowski, M.
Kowalczyk, A.
Toliński, T.
Powiązania:
https://bibliotekanauki.pl/articles/1813487.pdf
Data publikacji:
2008-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.80.Pv
65.40.Ba
75.20.Hr
Opis:
The specific heat of $YbNi_4Si$ has been analyzed considering the electronic contribution and the lattice contributions in frames of the Debye model. Based on the specific heat measurements, the electronic specific heat coefficient γ = 25 mJ $mol^{-1} K^{-2}$ and the Debye temperature $θ_D$ = 320 K were derived. This small value shows that $YbNi_4Si$ cannot be classified as a heavy fermion system. These studies are completed by magnetic susceptibility, X-ray photoemission spectroscopy, and electrical resistivity.
Źródło:
Acta Physica Polonica A; 2008, 113, 2; 641-644
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Bound Magnetic Polarons on Magnetic and Electrical Properties in Metallic n-Cd$\text{}_{0.95}$Mn$\text{}_{0.05}$Se
Autorzy:
Głód, P.
Sawicki, M.
Dietl, T.
Skośkiewicz, T.
Lenard, A.
Plesiewicz, W.
Powiązania:
https://bibliotekanauki.pl/articles/1931936.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.30.+h
71.38.+i
75.20.Hr
Opis:
Doping-induced contribution to the millikelvin magnetic susceptibility of Cd$\text{}_{0.95}$Mn$\text{}_{0.05}$Se:In has been found to undergo a maximum at n ≈ 2n$\text{}_{c}$, and to vanish for n ≥ 8n$\text{}_{c}$, where n$\text{}_{c}$ is the electron concentration corresponding to the metal-insulator transition. This confirms the presence, also in the metallic phase, of bound magnetic polarons. Their slow dynamics may account for hysteresis visible in our magnetoresistance data.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 173-175
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
Tytuł:
The Kondo Lattice Models and Magnetism for Cerium and Uranium Systems
Autorzy:
Coqblin, B.
Powiązania:
https://bibliotekanauki.pl/articles/1534596.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Mb
75.20.Hr
05.50.+q
64.60.Cn
Opis:
The interplay between the Kondo effect and magnetism is important in anomalous rare-earth and actinide systems and a brief review of the different Kondo lattice models is presented here. The first studied case is the classical Kondo lattice model with S = 1/2 spins for the 4f localized electrons, which describes the strong competition between the Kondo effect and magnetic ordering leading to small ordering temperatures less than roughly 10 K. The second reviewed case describes the underscreened Kondo lattice model with S = 1 spins for the 5f localized electrons, which can account for the coexistence of both the Kondo effect and the ferromagnetic order and, therefore, the large Curie temperatures observed in actinide compounds like UTe and $NpNiSi_2$; the question of the delocalization of the 5f electrons is also discussed here. The last case describes the competition between the "spin glass" behaviour, the Kondo effect and the magnetic ordering in disordered cerium alloys like $CeNi_{x}Cu_{1 - x}$ or $CeRh_{x}Pd_{1 - x}$ and several models used for the spin glass state are reviewed, as well as the occurrence of magnetic glass clusters.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 913-918
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pressure Induced Transitions in Heavy-Fermion Systems footnotemark
Autorzy:
Zhang, Sun
Dong, Yi-Qiao
Powiązania:
https://bibliotekanauki.pl/articles/1401900.pdf
Data publikacji:
2015-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Mb
75.20.Hr
71.28.+d
74.62.Fj
Opis:
In this paper, the electron-type heavy-fermion system and the hole-type heavy-fermion system are classified by means of the cell-volume difference between two typical valence states of f ions. Two kinds of transitions induced by pressure are studied theoretically within a unified picture presented for both two types of heavy-fermion systems. Among these transitions, the incoherence-to-coherence transition in the electron-type heavy-fermion system is confirmed intensively in experiments, while the coherence-to-incoherence transition in the hole-type heavy-fermion system is discussed as a prediction for further observations.
Źródło:
Acta Physica Polonica A; 2015, 128, 3; 389-393
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetism and Kondo Effect in Cerium and Uranium Compounds
Autorzy:
Coqblin, B.
Powiązania:
https://bibliotekanauki.pl/articles/1813756.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
75.30.Mb
05.50.+q
64.60.Cn
Opis:
A brief review of the Kondo lattice problem is presented, with a special emphasis on the underscreened Kondo effect in ferromagnetic-Kondo uranium compounds and on the spin glass-Kondo competition in disordered heavy fermion cerium alloys.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 391-394
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kondo Lattice and Magnetic Properties in Strongly Correlated Electron Systems
Autorzy:
Coqblin, B.
Powiązania:
https://bibliotekanauki.pl/articles/1810279.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
72.15.Qm
75.10.Nr
75.20.Hr
Opis:
We review here the magnetic properties of some strongly correlated electron systems and especially cerium and uranium compounds. The normal Kondo lattice model with a localized S=1/2 spin can account for the Kondo-magnetism competition observed in cerium or ytterbium systems, while the underscreened Kondo lattice model with a localized S=1 spin can well account for the ferromagnetism - Kondo coexistence observed in some uranium compounds such as UTe. Then, we discuss the spin glass-Kondo competition and present the resulting phase diagrams showing spin glass, Kondo and magnetically ordered phases observed in disordered heavy fermion cerium alloys such as $CeNi_xCu_{1-x}$ alloys.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 13-17
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure and Magnetic Properties of $La_{1-x}Ce_{x}Pb_3$ and $La_{1-x}Pr_{x}Pb_3$ Alloys
Autorzy:
Jezierski, A.
Kaczkowski, J.
Cichorek, T.
Powiązania:
https://bibliotekanauki.pl/articles/1207412.pdf
Data publikacji:
2014-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
71.20.Eh
71.20.Gj
75.20.Hr
Opis:
The electronic structure and magnetic properties of $La_{1-x}Ce_{x}Pb_3$ and $La_{1-x}Pr_{x}Pb_3$ are studied using the spin-polarized relativistic Korringa-Kohn-Rostoker coherent potential approximation method within the local spin density approximation. The calculated density of states at the Fermi level increases with the increase of the concentration. The dependence of spin and orbital magnetic moments of $La_{1-x}Ce_{x}Pb_3$ and $La_{1-x}Pr_{x}Pb_3$ (0 < x < 1) on the concentration is also reported. The densities of states at the Fermi energy are dominated by Ce(Pr) $4f_{5/2}$ and $4f_{7/2}$ states.
Źródło:
Acta Physica Polonica A; 2014, 125, 1; 111-114
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Electronic Structure of the RMn$\text{}_{2}$Ge$\text{}_{2}$ (R = Ca, Y, La, Ba) Antiferromagnets
Autorzy:
Toboła, J.
Malaman, B.
Venturini, G.
Powiązania:
https://bibliotekanauki.pl/articles/2013367.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.Mb
71.15.Nc
75.20.En
75.20.Hr
75.50.Ee
Opis:
The electronic structure of the tetragonal RMn$\text{}_{2}$Ge$\text{}_{2}$ (R = Ca, Y, La, Ba) antiferromagnets is presented using the self-consistent Korringa-Kohn-Rostoker method. According to the neutron refinements, two types of collinear antiferromagnetic structure are taken into account: AF$\text{}_{1}$ for YMn$\text{}_{2}$Ge$\text{}_{2}$ and AF$\text{}_{2}$ for the other compounds. The calculated magnetic moments on Mn: 2.17μ$\text{}_{B}$ (YMn$\text{}_{2}$Ge$\text{}_{2}$), 2.84 μ$\text{}_{B}$ (CaMn$\text{}_{2}$Ge$\text{}_{2}$), 2.95 μ$\text{}_{B}$ (LaMn$\text{}_{2}$Ge$\text{}_{2}$), and 3.47 μ$\text{}_{B}$ (BaMn$\text{}_{2}$Ge$\text{}_{2}$) remain in good agreement with the neutron data (in μ$\text{}_{B}$) 2.20, 2.67, 3.05, and 3.66, respectively. As seen on antiferromagnetic density of states, all systems are metallic, however BaMn$\text{}_{2}$Ge$\text{}_{2}$ is found near semimetallic limit. The total energy Korringa-Kohn-Rostoker computations on CaMn$\text{}_{2}$Ge$\text{}_{2}$, performed in both antiferromagnetic phases, result in preferring of the AF $\text{}_{2}$ structure.zap
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 761-765
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties and Electronic Structure of CeTIn (T = Ni, Cu, Pd, Au) Compounds
Autorzy:
Szytuła, A.
Penc, B.
Gondek, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/2047306.pdf
Data publikacji:
2007-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Eh
71.27.+a
75.20.Hr
79.60.-i
Opis:
The electronic structure of the ternary CeTIn (T = Ni, Cu, Pd, Au) compounds was investigated by means of X-ray photoelectron spectroscopy. Our interest was aimed mainly to the valence bands and the Ce3d core levels of investigated compounds. Analysis of the valence bands indicates that they are mainly determined by the Tnd band, whereas a share of the R4f states can be estimated to be about a few percent only. The analysis of the differential valence bands spectra between CeTIn and LaTIn analogues suggests that the Ce4f$\text{}^{1}$ ground states shift deeper below the Fermi level with an increase in the 4f level occupation factor. The analysis of the Ce3d spectra made on the basis of the Gunnarsson-Schönhammer model indicates the hybridization parameter equal to 148 meV for CeNiIn, 45 meV for CeCuIn, 177 meV for CePdIn, and 123 meV for CeAuIn.
Źródło:
Acta Physica Polonica A; 2007, 111, 4; 475-486
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cr-Based II-VI Semimagnetic Semiconductors
Autorzy:
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1931875.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Dg
75.30.Gw
75.50.Pp
75.20.Hr
78.30.Fs
Opis:
We review the magnetic and optical properties of recently grown Cr-based II-VI semimagnetic semiconductors. We focus on two features of these materials which distinguish them from other semimagnetic semiconductors: the particular magnetic behaviour of these crystals, resulting from the Cr$\text{}^{++}$ ion energy structure determined by a strong, static Jahn-Teller effect, and a ferromagnetic p-d exchange interaction, which is unique for II-VI semimagnetic semiconductors.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 85-93
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coqblin-Schrieffer Impurity with Local Exchange Coupling: a Perturbative Approach
Autorzy:
Stefański, P.
Powiązania:
https://bibliotekanauki.pl/articles/2013008.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Hf
71.20.Eh
72.15.Qm
75.20.Hr
Opis:
The Coqblin-Schrieffer one-impurity model with the additional local exchange interaction is studied within diagrammatic approach. The Ruderman-Kittel-Kasuya-Yoshida-type local exchange interaction between f electrons of the impurity and a channel of conduction electron l=0 partial waves is treated in the molecular field approximation. The perturbation expansion resummation for the Coqblin-Schrieffer hybridization mediated interaction vertex part is carried out in the ladder approximation yielding the formula for the Kondo temperature T$\text{}_{K}$ decreasing with increased local exchange. Moreover, the temperature divergence of the susceptibility at T$\text{}_{K}$ is shifted towards T=0. For some critical strength of the local exchange interaction the susceptibility approaches a Curie-type dependence as for an uncompensated impurity magnetic moment. A relation to the "Kondo disorder" model, which leads to the non-Fermi-liquid behavior, is discussed.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 385-388
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Polarized Transport through the Double-Dot System
Autorzy:
Sztenkiel, D.
Świrkowicz, R.
Powiązania:
https://bibliotekanauki.pl/articles/2044544.pdf
Data publikacji:
2005-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
72.15.Qm
72.25.-b
73.23.Hk
Opis:
Spin-dependent electron transport through two quantum dots in series attached to ferromagnetic electrodes is analyzed within the framework of the non-equilibrium Green function formalism. Regime of a weak coupling between the dots is investigated. I-V characteristics and tunnel magnetoresistance are calculated and discussed in detail.
Źródło:
Acta Physica Polonica A; 2005, 108, 5; 885-890
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Poor Mans Scaling Approach to the Kondo Effect in a Single Quantum Dot Asymmetrically Attached to Ferromagnetic Leads with Non-Collinear Magnetizations
Autorzy:
Wawrzyniak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1812020.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
72.15.Qm
72.25.-b
73.23.Hk
Opis:
The poor man's scaling technique is applied to the problem of electronic transport through a single quantum dot (with finite Coulomb repulsion) asymmetrically coupled to electrodes. The considered quantum dot is coupled to ferromagnetic electrodes, whose magnetic moments are non-collinear. The analysis and numerical illustration of spin splitting of the dot level as well as of the Kondo temperature on the coupling asymmetry is presented and discussed.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1421-1424
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetoresistance Anisotropy and Magnetic H-T Phase Diagram of $Tm_{0.996}Yb_{0.004}B_{12}$
Autorzy:
Sluchanko, N.
Azarevich, A.
Bogach, A.
Glushkov, V.
Demishev, S.
Gavrilkin, S.
Gabani, S.
Flachbart, K.
Shitsevalova, N.
Filipov, V.
Vanacken, J.
Moshchalkov, V.
Stankiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/1371466.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Gd
73.43.Qt
75.30.Kz
75.20.Hr
75.50.Ee
Opis:
The antiferromagnetic ground state has been studied by transverse magnetoresistance, heat capacity and magnetization measurements, which were carried out on high quality single crystals of $Tm_{0.996}Yb_{0.004}B_{12}$ dodecaboride in strong magnetic fields at liquid helium temperatures. Both antiferromagnetic-paramagnetic (AF-P) and spin-orientation (AF1-AF2) phase transitions have been observed, and allowed to construct a complicated magnetic H-T phase diagram for this compound. Strong magnetoresistance anisotropy was found both in AF states (ρ(H||[110])/ρ(H||[111])~ 1.2 at H~ 20 kOe) and at the critical field of AF-P transition $(H_{N}[100]$/$H_{N}[111]$~ 1.25) in this magnetic metal with a simple fcc crystal structure.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 332-333
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic and Transport Properties of $La_{0.67}Pb_{0.33}(Mn_{1-x}Co_x)O_3$
Autorzy:
Mihalik, M.
Kavečanský, V.
Maťaš, S.
Zentková, M.
Ammer, J.
Kellner, K.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/1813631.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.30.+h
72.80.Ga
75.20.Hr
75.30.Et
75.30.Vn
Opis:
Detailed studies of temperature dependences of magnetization, AC susceptibility and electrical resistance were performed on $La_{0.67}Pb_{0.33}(Mn_{1-x}Co_x)O_3$ ceramics with x = 0.01 and 0.1. Typical features of both compounds are the hysteretic behavior between the zero-field-cooled magnetization regime and the field-cooled magnetization regime, a very weak field dependence of a maximum in zero-field-cooled magnetization and practically no frequency dependence of the peak in AC susceptibility χ"(T). Anomalies in the electrical resistance connected with the ferromagnetic transition at $T_C$, the insulator-metal transitions at $T_p$ and the re-entrant metal-isolator transition at T* are field dependent pointing to magnetic origin of these transitions. Colossal magnetoresistance was observed in both compounds.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 251-254
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Poor Mans Scaling and Green Function Analysis of the Kondo Anomaly in Single-Level Quantum Dots
Autorzy:
Wawrzyniak, M.
Świrkowicz, R.
Wilczyński, M.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813883.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
72.15.Qm
72.25.-b
73.23.Hk
Opis:
Kondo effect in a single-level quantum dot attached to magnetic leads is studied theoretically by the "poor man's scaling" and non-equilibrium Green function methods. From the scaling equations we derive the Kondo temperature as a function of the model parameters - in particular as a function of the angle between magnetic moments. Transport characteristics, i.e. differential conductance and tunnel magnetoresistance associated with magnetization rotation, were calculated within the non-equilibrium Green function formalism based on the equation of motion method.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 553-556
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Transport through the Double-Dot System
Autorzy:
Świrkowicz, R.
Sztenkiel, D.
Powiązania:
https://bibliotekanauki.pl/articles/2038086.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
72.15.Qm
72.25.-b
73.23.Hk
Opis:
Electron tunnelling through two quantum dots in series is theoretically studied. A limit of intermediate coupling between the dots is considered. The non-equilibrium Green function formalism is used to calculate electric current and mean number of electrons accumulated on the dots. Lesser and retarded Green functions are calculated in the Hartree-Fock approximation with the use of the equation of motion method. Current flowing through the system calculated in dependency on gate voltages shows two resonant peaks, each peak with two additional shoulders. I-V characteristics and differential conductance in a resonance and out of resonance cases are calculated and discussed.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 523-528
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonequilibrium Kondo Effect in a Single-Channel Quantum Dot Asymmetrically Coupled to Two Ferromagnetic Reservoirs
Autorzy:
Świrkowicz, R.
Wilczyński, M.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/2037118.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
72.15.Qm
72.25.-b
73.23.Hk
Opis:
Nonequilibrium Kondo effect in a quantum dot asymmetrically coupled to two ferromagnetic metallic leads is analyzed theoretically. The nonequilibrium Green function technique is used to calculate density of states and electric current. The lesser and retarded (advanced) Green functions are calculated by the equation of motion method within a consistent approximation scheme. The case where one electrode is half-metallic is analyzed numerically in details.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 149-154
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-50 z 51

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