Physical properties of the non-centrosymmetric superconductor Nb0.18Re0.82

TL;DR

This study characterizes the superconducting and magnetic properties of Nb0.18Re0.82, a non-centrosymmetric superconductor, revealing its moderate coupling, isotropic gap, and potential for further single crystal investigations.

Contribution

First comprehensive measurement of magnetic, transport, and thermal properties of Nb0.18Re0.82, confirming its structure and superconducting parameters.

Findings

Superconducting transition at Tc ~ 8.8 K

Moderately coupled superconductor with ΔC/γTc = 1.86

Isotropic superconducting gap suggested by exponential decay of electronic specific heat

Abstract

We report the synthesis and measurements of magnetic, transport, and thermal properties of polycrystalline Nb0.18Re0.82, which has a superconducting transition at Tc ~ 8.8 K. The non-centrosymmetric alpha-Mn structure of the compound is confirmed by X-ray diffraction. Using the measured values for the lower critical field Hc1, upper critical field Hc2, and the specific heat C, we estimate the thermodynamic critical field Hc(0), coherence length {\xi}(0), penetration depth {\lambda}(0), and the Ginzburg-Landau parameter {\kappa}(0). The specific heat jump at Tc, {\Delta}C/{\gamma}Tc = 1.86, suggests that Nb0.18Re0.82 is moderately coupled superconductor. Below Tc the electronic specific heat decays exponentially, suggesting that the gap is isotropic. Our data suggests that the triplet admixture is weak in the polycrystalline form of compound. However, the estimated value of the upper critical field Hc2(0) is close to the calculated Pauli limit indicating the need for single crystal measurements.