$S$-wave pairing symmetry in non-centrosymmetric superconductor Re$_3$W

TL;DR

This study investigates the superconducting properties of Re$_3$W, revealing that despite its non-centrosymmetric structure, it exhibits conventional s-wave pairing symmetry, with two coexisting superconducting phases.

Contribution

It provides experimental evidence that non-centrosymmetric Re$_3$W maintains s-wave pairing symmetry, challenging assumptions about unconventional pairing in such materials.

Findings

Two superconducting phases coexist in Re$_3$W.

Re$_3$W exhibits s-wave pairing symmetry.

Absence of inversion symmetry does not induce unconventional pairing.

Abstract

The alloys of non-centrosymmetric superconductor, Re$_3$W, which were reported to have an $\alpha$-Mn structure [P. Greenfield and P. A. Beck, J. Metals, N. Y. \textbf{8}, 265 (1959)] with $T_\mathrm{c}=9 $K were prepared by arc melting. The ac susceptibility and low-temperature specific heat were measured on these alloys. It is found that there are two superconducting phases coexisting in the samples with $T_\mathrm{c1}\sim9 $K and $T_\mathrm{c2}\sim7 $K, both of which have a non-centrosymmetric structure as reported previously. By analyzing the specific heat data measured in various magnetic fields, we found that the absence of the inversion symmetry does not lead to the deviation from a s-wave pairing symmetry in Re$_3$W.