Depression of the superconducting transition temperature of the Heusler alloy Pd2YSn with the addition of magnetic rare-earth metals.

Abstract

The compound ${\mathrm{Pd}}_{2}$YSn, having the cubic Heusler L${2}_{1}$ structure, is superconducting with a transition temperature (${T}_{c}$) of 4.55 K. The effect on ${T}_{c}$ of replacing Y by other magnetic rare-earth metal has been investigated in the series ${\mathrm{Pd}}_{2}$${\mathrm{Y}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{R}}_{\mathrm{x}}$Sn (R=Gd, Dy, Ho, Er, Tm, and Yb). The depression in ${T}_{c}$ is the largest with Gd substitution. The initial rate of depression of ${T}_{c}$ shows deviation from the de Gennes function. The results of ${T}_{c}$ measurements are analyzed in terms of Abrikosov-Gor'kov theory, taking into account the effects of crystalline electric fields acting on rare-earth ions. Values of the density of states times the exchange constant, [N(0)${J}_{\mathrm{sf}{}^{2}}$], are derived from these measurements.