Atomic ordering andTcof narrow-band superconducting alloys

Abstract

We present a theoretical discussion for the transition temperature $T_c$ of superconducting alloys taking into account both the effects of composition and of atomic order. $T_c$ is found from the ensemble-averaged vertex equation for a Cooper pair written in the atomic representation. The application to new experimental data on the effect of long-range order on $T_c$ of ${\mathrm{Nb}}_3$Sn, ${\mathrm{V}}_3$Au, and ${\mathrm{V}}_3$Ga yields good agreement between theory and experiment.