Low-temperature properties of the Yb-based heavy-fermion antiferromagnets YbPtIn, YbRhSn, and YbNiGa

Abstract

The crystallographic and low-temperature properties of the equiatomic Yb-based compounds YbPtIn, YbRhSn (hexagonal ZrNiAl structure), and YbNiGa (orthorhombic $\ensuremath{\epsilon}$-TiNiSi structure) are studied by means of x-ray diffraction, magnetic susceptibility, magnetization, electrical resistivity $(\ensuremath{\rho}),$ magnetoresistance, thermoelectric power, and specific-heat ${(C}_{P})$ measurements. The magnetic susceptibility follows a Curie-Weiss law with effective magnetic moments close to the value of ${\mathrm{Yb}}^{3+}$ and shows strong magnetocrystalline anisotropy. At low temperature the three compounds exhibit the typical properties of antiferromagnetic (AFM) Kondo lattices, namely a logarithmic increase of $\ensuremath{\rho}(T),$ enhanced electronic ${C}_{P}$ coefficients ${\ensuremath{\gamma}}_{o},$ and a reduced entropy gain below the ordering temperature. The values of ${\ensuremath{\gamma}}_{o}>350 {\mathrm{m}\mathrm{J}/\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{}\mathrm{K}}^{2}$ are among the largest of known Yb-based magnetic Kondo lattices. Two AFM transitions in each compound evidence a competition between single-ion anisotropy and frustration of the magnetic interactions due to the topology of the underlying crystal structure. The ground-state properties are discussed and compared with those of other f-electron compounds showing similar characteristics concerning magnetic frustration.