Complex superconductivity in the noncentrosymmetric compound Re$_{6}$Zr

TL;DR

This study investigates the superconducting properties of Re$_{6}$Zr, revealing a transition at 6.7 K, with evidence suggesting a predominantly full gap but possible point nodes, influenced by noncentrosymmetric structure.

Contribution

First comprehensive analysis of Re$_{6}$Zr's electronic structure, superconducting parameters, and effects of doping and pressure, highlighting its complex superconductivity with mixed pairing components.

Findings

Superconducting transition at ~6.7 K

Full superconducting gap likely, with possible point nodes

Weak to moderate triplet pairing contribution

Abstract

We report the electronic structure, synthesis, and measurements of the magnetic, transport, and thermal properties of the polycrystalline noncentrosymmetric compound Re$_{6}$Zr. We observed a bulk superconducting transition at temperature $T_{c}$ $\sim$ 6.7 K, and measured the resistivity, heat capacity, thermal conductivity, and the London penetration depth below the transition, as well as performed doping and pressure studies. From these measurements we extracted the critical field, and the superconducting parameters of Re$_{6}$Zr. Our measurements indicate a relatively weak to moderate contribution from a triplet component to the order parameter, and favor a full superconducting gap, although we cannot exclude the existence of point nodes based on our data.