Electronic density of states andTcinNb3Sn under pressure

Abstract

We have determined the effect of hydrostatic pressure on the electronic heat-capacity coefficient $\gamma$ of transforming ${\mathrm{Nb}}_3$Sn through measurements of the superconducting transition temperature $T_c$, the temperature derivative of the upper critical field near $T_c$, and the residual resistivity. We find that $\gamma$ and the bare density of electronic states are suppressed by pressure. Results are discussed in terms of a pressure-dependent $d$-band occupancy. From an analysis of the density-of-states change under pressure, we infer the existence of a substantial electronic contribution to the Grüneisen parameter of ${\mathrm{Nb}}_3$Sn.