BCS-like superconductivity in the noncentrosymmetric compounds NbxRe1−x(0.13≤x≤0.38)

Abstract

We present research on the superconducting properties of Nb${}_{x}$Re${}_{1\ensuremath{-}x}$ ($x=0.13$--0.38) obtained by measuring the electrical resistivity $\ensuremath{\rho}(T)$, magnetic susceptibility $\ensuremath{\chi}(T)$, specific heat ${C}_{P}(T)$, and London penetration depth $\ensuremath{\Delta}\ensuremath{\lambda}(T)$. It is found that the superconducting transition temperature ${T}_{c}$ decreases monotonically with an increase of $x$. The upper critical field ${B}_{c2}(T)$ for various $x$ can be nicely scaled by its corresponding ${T}_{c}$. The electronic specific heat ${C}_{e}(T)/T$, penetration depth $\ensuremath{\Delta}\ensuremath{\lambda}(T)$, and superfluid density ${\ensuremath{\rho}}_{s}(T)$ demonstrate exponential behavior at low temperatures and can be well fitted by a one-gap BCS model. The residual Sommerfeld coefficient ${\ensuremath{\gamma}}_{0}(B)$ in the superconducting state follows a linear field dependence. All these properties suggest an $s$-wave BCS-type of superconductivity with a very large ${B}_{c2}(0)$ for Nb${}_{x}$Re${}_{1\ensuremath{-}x}$ ($0.13\ensuremath{\le}x\ensuremath{\le}0.38$).