Magnetic behavior in a series of cerium ternary intermetallics:Ce2T2In (T=Ni, Cu, Rh, Pd, Pt, and Au)

Abstract

A group of ternary cerium compounds ${\mathrm{Ce}}_2$ ${\mathit{T}}_2$In (T=Ni, Cu, Rh, Pd, Pt, and Au) has been synthesized. As found from single-crystal and powder x-ray-diffraction studies, all these phases crystallize in a primitive tetragonal structure of the ${\mathrm{Mo}}_2$ ${\mathrm{FeB}}_2$ type. Magnetic measurements (magnetization, dc and ac susceptibility) have revealed the physical properties of these intermetallics to be mainly governed by the 4f-d hybridization. Depending on the filling of the transition metal d band the ground state in ${\mathrm{Ce}}_2$ ${\mathit{T}}_2$In changes from a nonmagnetic to a well localized magnetic regime. It was proved that ${\mathrm{Ce}}_2$ ${\mathrm{Ni}}_2$In and ${\mathrm{Ce}}_2$ ${\mathrm{Rh}}_2$In are intermediate-valence systems, ${\mathrm{Ce}}_2$ ${\mathrm{Pt}}_2$In is a strongly temperature-dependent paramagnet, whereas ${\mathrm{Ce}}_2$ ${\mathrm{Cu}}_2$In, ${\mathrm{Ce}}_2$ ${\mathrm{Pd}}_2$In, and ${\mathrm{Ce}}_2$ ${\mathrm{Au}}_2$In order magnetically at low temperatures. Measurements of the electrical resistivity have corroborated the intermediate-valence behavior in ${\mathrm{Ce}}_2$ ${\mathrm{Ni}}_2$In and ${\mathrm{Ce}}_2$ ${\mathrm{Rh}}_2$In. In turn, the resistivity of the remaining ternaries studied was found to be determined by an interplay of Kondo scattering and crystal-field effects. For ${\mathrm{Ce}}_2$ ${\mathrm{Pt}}_2$In which behaves like a spin-fluctuating system due to strong Kondo-type interactions a nonmagnetic heavy-fermion ground state probably occurs. © 1996 The American Physical Society.