The crystallographic and low-temperature properties of the equiatomic Yb-based compounds YbPtIn, YbRhSn (hexagonal ZrNiAl structure), and YbNiGa (orthorhombic $\epsilon$-TiNiSi structure) are studied by means of x-ray diffraction, magnetic susceptibility, magnetization, electrical resistivity $\left(\rho \right),$ 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 $\rho \mathrm{}\left(T\right),$ enhanced electronic $C_P$ coefficients ${\gamma }_o,$ and a reduced entropy gain below the ordering temperature. The values of ${\gamma }_o>350\mathrm{}\hspace{0.5em}{\mathrm{m}\mathrm{J}/\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{}\mathrm{K}}^2$ 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.

• Received 22 April 1999

DOI:https://doi.org/10.1103/PhysRevB.61.9467