Antiferromagnetic Kondo lattice in the layered compoundCePd1−xBi2and comparison to the superconductorLaPd1−xBi2

Abstract

The layered compound ${\mathrm{CePd}}_{1\ensuremath{-}x}{\mathrm{Bi}}_{2}$ with the tetragonal ${\mathrm{ZrCuSi}}_{2}$-type structure was obtained from excess Bi flux. Magnetic susceptibility data of ${\mathrm{CePd}}_{1\ensuremath{-}x}{\mathrm{Bi}}_{2}$ show an antiferromagnetic ordering below 6 K and are anisotropic along the $c$ axis and the $ab$ plane. The anisotropy is attributed to crystal-electric-field (CEF) effects and a CEF model which is able to describe the susceptibility data is given. An enhanced Sommerfeld coefficient $\ensuremath{\gamma}$ of 0.191 J mol $\mathrm{Ce}{}^{\ensuremath{-}1} \mathrm{K}{}^{\ensuremath{-}2}$ obtained from specific-heat measurement suggests a moderate Kondo effect in ${\mathrm{CePd}}_{1\ensuremath{-}x}{\mathrm{Bi}}_{2}$. Other than the antiferromagnetic peak at 6 K, the resistivity curve shows a shoulderlike behavior around 75 K which could be attributed to the interplay between Kondo and CEF effects. Magnetoresistance and Hall-effect measurements suggest that the interplay reconstructs the Fermi-surface topology of ${\mathrm{CePd}}_{1\ensuremath{-}x}{\mathrm{Bi}}_{2}$ around 75 K. Electronic structure calculations reveal that the Pd vacancies are important to the magnetic structure and enhance the CEF effects which quench the orbital moment of Ce at low temperatures.