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1

Low-Temperature Physical Properties of Single-Crystalline EuCoGe₃ and EuRhGe₃

100%

Bednarchuk O. , Kaczorowski D.

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nr 2

418-420

EN

Since a few years europium-based intermetallics have been attracting more and more attention due to their intriguing physical properties with anomalous behaviours in magnetically ordered states. Here, we report on the formation and the bulk physical properties of two tetragonal compounds EuCoGe₃ and EuRhGe₃, studied on high-quality single-crystalline specimens. In both materials, the Eu ions are in their divalent state, which gives rise to an antiferromagnetic ordering below T_{N} = 15.4 K and T_{N} = 11.3 K, respectively. In addition, EuCoGe₃ exhibits a successive antiferromagnetic phase transition at T₂ = 13.4 K. Based on some characteristic features in the temperature variations of the magnetic susceptibility, specific heat and electrical resistivity, we suggest that in both germanides an amplitude modulated magnetic structure develops below the respective T_{N}, with the Eu magnetic moments directed along the crystallographic [001] axis in EuCoGe₃ and perpendicular to this direction in EuRhGe₃.

2

Antiferromagnetic Order in the Half-Heusler Phase TbPdBi

80%

Pavlosiuk O. , Kleinert M. , Wiśniewski P. , Kaczorowski D.

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nr 3

498-500

EN

Single crystals of TbPdBi, a representative of the group of half-Heusler bismuthides, were studied by means of magnetic susceptibility, heat capacity, electrical resistivity, magnetostriction and thermal expansion measurements. The compound was characterized as an antiferromagnet with the Néel temperature T_{N} ≈5.3 K. Neutron diffraction experiment confirmed the antiferromagnetic ordering and yielded the propagation vector k=(1/2,1/2,1/2). Remarkably, this k vector is in accord with the recently developed theory of antiferromagnetic topological insulators.

3

Quantum Interference in Disordered Ferromagnet U₂NiSi₃

80%

Gnida D. , Szlawska M. , Wiśniewski P. , Kaczorowski D.

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nr 2

451-453

EN

A single-crystalline sample of disordered ferromagnetic U₂NiSi₃ was investigated by means of electrical resistivity measurements under ambient and high hydrostatic pressure. Temperature dependences of the electrical resistivity clearly reveal interplay of the ferromagnetic ordering and quantum interference effects resulting from crystallographic disorder. Electron-electron interaction manifests itself as a T^{0.5} increase in the in-plane and out-of-plane electrical resistivity below 5 K. Weak localization is observed solely in the ab-plane as a linear-in-T contribution to resistivity, which suggests that internal magnetic field does not break the interference of scattered electron waves in ab-plane. Applied hydrostatic pressure does not affect the T^{0.5} electron-electron interaction contribution, however it diminishes the impact of weak localization on the ab-plane resistivity.

4

Magnetic and Electronic Properties in Series of GdT_{x}Ga_{4-x} Solid Solutions (T = Ni or Cu)

80%

Wiśniewski P. , Gorzelniak R. , Kaczorowski D.

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nr 2

382-384

EN

We present results of extensive measurements of magnetic susceptibility, electrical resistance, specific heat and thermoelectric power of two series of solid solutions GdNi_{x}Ga_{4-x} and GdCu_{x}Ga_{4-x}, for ranges of doping x from 0.6 to 1 and from 1 to 1.5, respectively. All studied phases display the Curie-Weiss behaviour of magnetic susceptibility and antiferromagnetic ordering at temperatures below 23 K. Substitution of gallium with transition metal atoms has strong influence on Néel temperatures of all studied phases, shifting them by few K, depending on x. Metamagnetic-like anomalies are observed for some compositions. Behaviour of the electrical resistivity reveals metallic nature of all samples. Their magnetic ordering is reflected in low-temperature anomalies of the resistivity and the heat capacity.

5

Giant Magnetoresistance and Shubnikov-de Haas Effect in LuSb

71%

Kleinert M. , Pavlosiuk O. , Swatek P. , Kaczorowski D. , Wiśniewski P.

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nr 3

538-540

EN

Single-crystals of LuSb were investigated by means of electrical resistivity and magnetoresistance measurements. The compound was found to exhibit giant magnetoresistance exceeding 3000%, low-temperature resistivity plateau, and Shubnikov-de Haas oscillations. It was characterized as a semimetal with nearly balanced contributions of electron and hole carriers to the magnetotransport properties. The experimental findings, supported by the results of electronic structure calculations, proved that the magnetotransport in LuSb can be described in the scope of 3D multi-band Fermi surface model without topologically non-trivial electronic states.

6

Magnetic Ordering in ErFe_{0.3}Ge_{2} and ErNi_{0.65}Ge_{2} Compounds

71%

Penc B. , Arulraj A. , Kaczorowski D. , Szytuła A. , Wawrzyńska E.

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nr 4

595-598

EN

The magnetic ordering in ErFe_{0.3}Ge_{2} and ErNi_{0.65}Ge_{2} compounds crystallizing in the orthorhombic structure of the CeNiSi_{2}-type has been investigated by neutron diffraction and magnetic measurements. The Er magnetic moments have been found to order antiferromagnetically below 2.5 K in ErFe_{0.3}Ge_{2} and 2.3 K in ErNi_{0.65}Ge_{2}. The magnetic structure of the former compound can be described by the propagation vector k = (0.044(1), 0, 0.384(1)). The Er magnetic moments are aligned along the a-axis and alternate with the sequence ++- in the unit cell. At 1.5 K they are equal to 5.9(1) μ_{B}. In contrast, the magnetic unit cell of ErNi_{0.65}Ge_{2} has been established to be equal to the chemical one. The magnetic moments in this compound are arranged in a collinear manner pointing along the a-axis with the sequence +-+-. The Er moment value measured at 1.5 K is 2.90(8) μ_{B}.

7

Magnetic Properties of RSn_{2} (R = Tb, Dy) Compounds

71%

Szytuła A. , Kaczorowski D. , Gondek Ł. , Czub J. , Nenkov K.

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nr 4

586-589

EN

Polycrystalline samples of TbSn_{2} and DySn_{2} were studied by means of magnetic susceptibility, electrical resistivity and heat capacity measurements. Both compounds have been found to order antiferromagnetically at low temperatures with some extra features in the ordered state due to changes in their magnetic structures. The two stannides exhibit metallic conductivity. The estimated crystal field levels splitting of Tb^{3+} and Dy^{3+} ground multiplets do not exceed 75 K.