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1

Magnetic Susceptibility of HgTe⟨Mn,Fe,Cr⟩

100%

Frasunyak V. M., Gavaleshko M. P.

Acta Physica Polonica A

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1995

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vol. 88

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issue 4

715-718

EN

The results of the investigations of magnetic susceptibility (χ) of HgTe⟨Mn,Fe,Cr⟩ with N_{3d} < 10^{21} cm^{-3} in temperature range of 80-290 K and for magnetic fields of 0.4-9 kOe are presented. It was shown that χ_{Mn}(T) and χ_{Fe}(T) in HgTe⟨Mn,Fe⟩ are described by Curie law and for Ν_{3d} > 10^{21} cm^{-3} - by Curie-Weiss law with negative value of θ_{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⟩.

2

Magnetization of Pb_{1-x}Cr_{x}Te Semimagnetic Semiconductor

63%

Mac W., Story T., Twardowski A.

Acta Physica Polonica A

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1995

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vol. 87

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issue 2

492-494

EN

We present experimental studies of magnetization of Pb_{1-x}Cr_{x}Te (x ≤ 0.01) crystals. The reasonable description of the data is obtained for a composition of x ≤ 0.001 using Cr^{+++} model (Brillouin type paramagnetism S = 3/2).

3

Magnetic Properties of Icosahedral (Au,Cu)-Al-Yb Quasicrystals

63%

Oki S., Hiroto T., Muro Y., Tamura R.

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vol. 126

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issue 2

553-555

EN

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.

4

Low Temperature Transport and Magnetic Properties of SmB_{6}

63%

Gabani S., Flachbart K., Pavlík V., Konovalova E., Paderno Y., Herrmannsdörfer T.

Acta Physica Polonica A

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2000

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vol. 97

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issue 3

419-422

EN

We present results of transport and magnetic properties of three single-crystalline samples of the intermediate valence small-gap semiconductor SmB_{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^{3+} ions or by a small amount of in-gap magnetic 4f^{5}5d^{1} states.

5

Is the Magnetism of HgSe:Fe Clearly Understood?

63%

Dybko K., Łusakowski A., Kossut J., Arciszewska M., Linden P. J. E. M. v., Wittlin A., Perenboom J. A. A. J., Mycielski A.

Acta Physica Polonica A

|

1995

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vol. 87

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issue 1

193-196

EN

The high magnetic field magnetization measurements of low composition Hg_{1-x}Fe_{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^{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^{2+} is well described in the model of isolated Fe^{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^{3+} and Fe^{2+} present simultaneously (x = 0.003) is shown to be different from a simple additive superposition of the contributions due to Fe^{3+} and Fe^{2+} subsystems. The possible origin of this discrepancy is discussed.

6

Electronic and Magnetic Properties of ThCo_4B

63%

Szajek A.

Acta Physica Polonica A

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2008

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vol. 113

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issue 1

283-286

EN

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.

7

The Mott Transition in Disordered Systems

63%

Dobrosavljević V., Kotliar G.

Acta Physica Polonica A

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1994

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vol. 85

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issue 1

21-38

EN

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.

8

Magnetic Behaviour in CeNiGa_{2} and Ce_{2}Ni_{2}Ga

63%

Kaczorowski D., Rogl P.

Acta Physica Polonica A

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1997

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vol. 92

|

issue 2

289-293

EN

The bulk properties of CeNiGa_{2} and Ce_{2}Νi_{2}Ga were studied by means of magnetic susceptibility, magnetization and electrical resistivity measurements. It was found that CeNiGa_{2} is an antiferromagnetically ordered dense Kondo system whereas Ce_{2}Ni_{2}Ga exhibits a fluctuating valence behaviour.

9

Ab Initio Study of Electronic and Magnetic Structure and Structural Phase Transition of (Fe_{1 - x}Mn_{x})_2P_{1 - y}Ge_{y} Alloys

63%

Deniszczyk J., Woźniakowski A., Kolano R., Kolano-Burian A.

|

EN

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.

10

Jahn-Teller Center as Quasiparticle of Fractional Statistics

63%

Sobolewski A. L.

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EN

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.

11

Anisotropy of Magnetic Interactions in HgFeSe

63%

Wilamowski Z., Przybylińska H., Joss W., Guillot M.

|

EN

Magnetic properties (susceptibility, high-field torque and magnetization) of cubic HgFeSe are analyzed. Van Vleck magnetism of Fe^{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.

12

Importance of the Spin-Orbit Coupling for 3d-Ion Compounds: the Case of NiO

63%

Radwański R., Ropka Z.

Acta Physica Polonica A

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2000

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vol. 97

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issue 5

963-965

EN

The orbital and spin moment of the Ni^{2+} ion in NiO has been calculated at 0 K to be 0.54 μ_{B} and 1.99 μ_{B} respectively. Such large orbital moment, more than 20% of the total moment of 2.53 μ_{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.

13

Kondo Lattice and Magnetic Properties in Strongly Correlated Electron Systems

51%

Coqblin B.

Acta Physica Polonica A

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2009

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vol. 115

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issue 1

13-17

EN

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.

14

Influence of Bound Magnetic Polarons on Magnetic and Electrical Properties in Metallic n-Cd_{0.95}Mn_{0.05}Se

51%

Głód P., Sawicki M., Dietl T., Skośkiewicz T., Lenard A., Plesiewicz W.

Acta Physica Polonica A

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1995

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vol. 87

|

issue 1

173-175

EN

Doping-induced contribution to the millikelvin magnetic susceptibility of Cd_{0.95}Mn_{0.05}Se:In has been found to undergo a maximum at n ≈ 2n_{c}, and to vanish for n ≥ 8n_{c}, where n_{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.

15

Nonequilibrium Kondo Effect in a Single-Channel Quantum Dot Asymmetrically Coupled to Two Ferromagnetic Reservoirs

51%

Świrkowicz R., Wilczyński M., Barnaś J.

Acta Physica Polonica A

|

2004

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vol. 105

|

issue 1-2

149-154

EN

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.

16

Metals and Semimetals with Strongly Correlated Electrons

51%

Fulde P.

Acta Physica Polonica A

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1997

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vol. 91

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issue 1

67-76

EN

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_{2-x}Ce_{x}CuO_{4}. The other is operative in the semimetal Yb_{4}As_{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.

17

Aspects of Magnetism in Heavy-Electron Metals

51%

Ott H.

Acta Physica Polonica A

|

1994

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vol. 85

|

issue 1

7-19

EN

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.

18

Mixed-Valence State in Yb_2CuGe_6

51%

Szytuła A., Penc B., Konyk M., Winiarski A.

Acta Physica Polonica A

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2008

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vol. 113

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issue 4

1205-1209

EN

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.

19

Electronic Transport through the Double-Dot System

51%

Świrkowicz R., Sztenkiel D.

Acta Physica Polonica A

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2004

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vol. 105

|

issue 6

523-528

EN

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.

20

Pressure Induced Transitions in Heavy-Fermion Systems footnotemark

51%

Zhang S., Dong Y.-Q.

Acta Physica Polonica A

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2015

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vol. 128

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issue 3

389-393

EN

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.

Refine search results

Magnetic Susceptibility of HgTe⟨Mn,Fe,Cr⟩

Magnetization of Pb_{1-x}Cr_{x}Te Semimagnetic Semiconductor

Magnetic Properties of Icosahedral (Au,Cu)-Al-Yb Quasicrystals

Low Temperature Transport and Magnetic Properties of SmB_{6}

Is the Magnetism of HgSe:Fe Clearly Understood?

Electronic and Magnetic Properties of ThCo_4B

The Mott Transition in Disordered Systems

Magnetic Behaviour in CeNiGa_{2} and Ce_{2}Ni_{2}Ga

Ab Initio Study of Electronic and Magnetic Structure and Structural Phase Transition of (Fe_{1 - x}Mn_{x})_2P_{1 - y}Ge_{y} Alloys

Jahn-Teller Center as Quasiparticle of Fractional Statistics

Anisotropy of Magnetic Interactions in HgFeSe

Importance of the Spin-Orbit Coupling for 3d-Ion Compounds: the Case of NiO

Kondo Lattice and Magnetic Properties in Strongly Correlated Electron Systems

Influence of Bound Magnetic Polarons on Magnetic and Electrical Properties in Metallic n-Cd_{0.95}Mn_{0.05}Se

Nonequilibrium Kondo Effect in a Single-Channel Quantum Dot Asymmetrically Coupled to Two Ferromagnetic Reservoirs

Metals and Semimetals with Strongly Correlated Electrons

Aspects of Magnetism in Heavy-Electron Metals

Mixed-Valence State in Yb_2CuGe_6

Electronic Transport through the Double-Dot System

Pressure Induced Transitions in Heavy-Fermion Systems footnotemark