Electronic structure, superconductivity, and spin fluctuations in theA15compoundsA3B:A=V, Nb;B=Ir,Pt,Au

Abstract

The electronic structure of six $A15$ compounds ${\mathrm{V}}_{3}$Ir, ${\mathrm{V}}_{3}$Pt, ${\mathrm{V}}_{3}$Au, ${\mathrm{Nb}}_{3}$Ir, ${\mathrm{Nb}}_{3}$Pt, and ${\mathrm{Nb}}_{3}$Au has been determined by means of self-consistent semirelativistic linear muffin-tin orbital band calculations. Parameters related to superconductivity such as electron-phonon coupling, transition temperature, electronic specific heat, and magnetic exchange enhancement are derived from the electronic-structure results. Generally the results obtained agree well with experimental values, with the exception of ${\mathrm{Nb}}_{3}$Pt and ${\mathrm{V}}_{3}$Au. In the former compound the density of states (DOS) has a sharp increase at ${E}_{F}$ making the exact DOS value uncertain. In ${\mathrm{V}}_{3}$Au the high calculated ${T}_{c}$ and the Stoner factor indicate that spin fluctuations may be limiting the ${T}_{c}$.