Search results

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

Jahn-Teller Center as Quasiparticle of Fractional Statistics

63%

Sobolewski A. L.

Acta Physica Polonica A

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1995

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vol. 88

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issue 2

305-313

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.

3

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.

Acta Physica Polonica A

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2012

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vol. 121

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issue 5-6

1162-1164

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.

4

Anisotropy of Magnetic Interactions in HgFeSe

63%

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

Acta Physica Polonica A

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1992

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vol. 82

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issue 4

689-692

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.

5

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

|

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.

6

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

|

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.

7

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

|

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.

8

Electronic and Magnetic Properties of ThCo_4B

63%

Szajek A.

|

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.

9

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.

10

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

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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.

11

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).

12

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

63%

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

Acta Physica Polonica A

|

2014

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vol. 126

|

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.

13

Substitution Study on the Coherent Kondo State in CeCu_{5}In

51%

Kaczorowski D., Kalychak Y., Zaremba V.

Acta Physica Polonica A

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2000

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vol. 97

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issue 1

189-192

EN

Ternary alloys CeCu_{5-x}In_{1+x} were studied by means of magnetic and electrical resistivity measurements. In CeCu_{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.

14

Strongly Correlated Electron Behaviour in CeT_2Al_8 (T~=~Fe,~Co)

51%

Ghosh S., Strydom A.

Acta Physica Polonica A

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2012

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vol. 121

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issue 5-6

1082-1084

EN

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.

15

Magnetic Properties of MeB_{50} (Me = 3d Atom) Compounds

51%

Panfilov A., Grechnev G., Filipov V., Lyashchenko A., Levchenko G.

Acta Physica Polonica A

|

2014

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vol. 126

|

issue 1

400-401

EN

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.

16

Two Kondo Impurities in Armchair Graphene Nanoribbon

51%

Lipiński S., Krychowski D.

Acta Physica Polonica A

|

2012

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vol. 121

|

issue 5-6

1063-1065

EN

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.

17

Anisotropy of Susceptibility and Optical investigation of the Antiferromagnetic phase Transition in U_{1-x}Ce_{x}Ru_{2}Si_{2}

51%

Mihalik M., Maťaš S., Macko D., Timko M., Menovsky A. A.

Acta Physica Polonica A

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1997

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vol. 91

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issue 2

351-354

EN

Temperature dependence of magnetic susceptibility of U_{1-x}Ce_{x}Ru _{2}Si_{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_{0.99}Ce_{0.01} Ru_{2}Si_{2} single crystal have been studied for the first time. The measurements support the assumption that the origin of magnetic ordering in U_{0.99}Ce_{0.01}Ru_{2}Si_{2} is the same as in heavy-fermion superconductor URu_{2}Si_{2} and can be interpreted as being due to a spin-density-wave gap.

18

Seebeck Coefficient of CePd_{3}

51%

Mahan G., Bartkowiak M.

Acta Physica Polonica A

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2000

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vol. 97

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issue 1

37-42

EN

Rare earth compounds have potential applications in thermoelectric devices due to their large value of conductivity and Seebeck coefficient. CePd_{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^{1} level.

19

Anomalous Transport and Thermal Properties of the Solid Solutions U_{1-x}Th_{x}Cu_{5}M (M = Al, Ga, In and Sn)

51%

Troć R., Tran V., Kaczorowski D., Czopnik A.

Acta Physica Polonica A

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2000

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vol. 97

|

issue 1

25-35

EN

UCu_{5}M-type compounds are moderate heavy fermion systems with an antiferromagnetic order below T_{N} = 18, 16-25, and 25 K for M = Al, (Ga, In), and In, respectively, and a ferrimagnetic order with T_{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_{1-x}Th_{x}Cu_{5}M. Only in the case of UCu_{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_{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_{5}(In_{1-x}Ga_{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.

20

On Magnetic Impurities in Gapless Fermi Systems

51%

Borkowski L. S.

Acta Physica Polonica A

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1997

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vol. 91

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issue 2

359-362

EN

In ordinary metals, antiferromagnetic exchange between conduction electrons and a magnetic impurity leads to screening of the impurity spin below the Kondo temperature, T_{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_{K}. The behavior of an Anderson impurity in a model with a power-law density of states, ρ(ε) ∝ |ε|^{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.

Refine search results

Magnetic Susceptibility of HgTe⟨Mn,Fe,Cr⟩

Jahn-Teller Center as Quasiparticle of Fractional Statistics

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

Anisotropy of Magnetic Interactions in HgFeSe

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

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

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

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

Substitution Study on the Coherent Kondo State in CeCu_{5}In

Strongly Correlated Electron Behaviour in CeT_2Al_8 (T~=~Fe,~Co)

Magnetic Properties of MeB_{50} (Me = 3d Atom) Compounds

Two Kondo Impurities in Armchair Graphene Nanoribbon

Anisotropy of Susceptibility and Optical investigation of the Antiferromagnetic phase Transition in U_{1-x}Ce_{x}Ru_{2}Si_{2}

Seebeck Coefficient of CePd_{3}

Anomalous Transport and Thermal Properties of the Solid Solutions U_{1-x}Th_{x}Cu_{5}M (M = Al, Ga, In and Sn)

On Magnetic Impurities in Gapless Fermi Systems