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1

Angular Magnetoresistance of a Possible Kondo Insulator CeOs₄Sb₁₂ Measured at Ultra-Low Temperatures

100%

Bochenek Ł., Cichorek T.

Acta Physica Polonica A

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2016

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vol. 130

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issue 2

600-603

EN

Angular magnetoresistance of the filled skutterudite compound CeOs₄Sb₁₂ has been investigated along the [110] direction. Distinct differences between the angular magnetoresistance data at T = 0.55 K and 4.2 K coincide with a developing of spin-density waves at T ≈ 1.7 K in B = 5 T. Magnetoresistance experiments have been performed on a self-made assembly utilizing a commercial piezoelectric rotator.

2

Electronic Structure and Magnetic Properties of La_{1-x}Ce_{x}Pb_3 and La_{1-x}Pr_{x}Pb_3 Alloys

81%

Jezierski A., Kaczkowski J., Cichorek T.

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vol. 125

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issue 1

111-114

EN

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.

3

Specific Heatof the Filled Skutterudite Superconductor LaOs₄As₁₂

81%

Juraszek J., Henkie Z., Cichorek T.

Acta Physica Polonica A

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2016

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vol. 130

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issue 2

597-599

EN

We investigated low-temperature specific heat of the filled skutterudite compound LaOs₄As₁₂ with a transition temperature T_{c} = 3.2 K. A moderate size of a specific-heat jump points at a weak electron-phonon coupling in this material. At T < T_{c}, the electronic contribution to the specific heat was found to be at variance with the predictions for an s-wave superconductor with one energy gap. Additionally, we observed an upward curvature of the upper critical field near the transition temperature. Both features provide some indications towards multiband superconductivity, although anisotropy effects as a viable cause of the observed anomalies in LaOs₄As₁₂ cannot be excluded. Similarities to a probable two-band superconductor LaRu₄As₁₂ are discussed.

4

Magnon and Soliton Excitations in the Carrier-Poor, One-Dimensional S=1/2 Antiferromagnet Yb_{4}As_{3}

52%

Steglich F., Köppen M., Gegenwart P., Cichorek T., Wand B., Lang M., Thalmeier P., Schmidt B., Aoki H., Ochiai A.

Acta Physica Polonica A

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2000

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vol. 97

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issue 1

91-100

EN

The semimetallic quasi-one-dimensional S=1/2 Heisenberg antiferromagnet Yb_{4}As_{3} was studied by low-temperature measurements of the specific heat C(T,B), thermal expansion α(T,B), and thermal conductivity ĸ(T,B). At finite magnetic fields (B≤12 T) we observed the following distinct anomalies: (1) the magnon contribution to C(T,0), γ T, with large coefficient γ ≈ 200 mJ/(K^{2}mol), becomes strongly reduced with field, and (2) a broad hump in C(T,B=const) is induced at slightly higher temperatures. (3) The latter corresponds to a pronounced peak in α(T,B=const) as well as (4) to a broad minimum in ĸ(T,B= const)/ĸ(T,0). These anomalies are well described by the classical sine-Gordon solution of a one-dimensional Heisenberg antiferromagnet with a weak easy-plane anisotropy. However, the soliton-rest energy deduced from the experimental results depends on the magnetic field like E_{S} ~ B^{ν}, with an exponent ν ≈ 0.66, while the classical sine-Gordon model requires ν=1. Thus, our results suggest an alternative description of soliton excitations in an antiferromagnetic S=1/2 Heisenberg chain in terms of the quantum sine-Gordon model, for which an exponent ν=2/3 is appropriate.

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4 Acta Physica Polonica A

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4 Cichorek T.

1 Aoki H.

1 Bochenek Ł.

1 Gegenwart P.

1 Henkie Z.

1 Jezierski A.

1 Juraszek J.

1 Kaczkowski J.

1 Köppen M.

1 Lang M.

1 Ochiai A.

1 Schmidt B.

1 Steglich F.

1 Thalmeier P.

1 Wand B.

Angular Magnetoresistance of a Possible Kondo Insulator CeOs₄Sb₁₂ Measured at Ultra-Low Temperatures

Electronic Structure and Magnetic Properties of La_{1-x}Ce_{x}Pb_3 and La_{1-x}Pr_{x}Pb_3 Alloys

Specific Heatof the Filled Skutterudite Superconductor LaOs₄As₁₂

Magnon and Soliton Excitations in the Carrier-Poor, One-Dimensional S=1/2 Antiferromagnet Yb_{4}As_{3}