Superconducting and normal state properties of high entropy alloy Nb-Re-Hf-Zr-Tiinvestigated by muon spin relaxation and rotation

TL;DR

This study investigates the superconducting properties of a high entropy alloy Nb-Re-Hf-Zr-Ti using various experimental techniques, revealing bulk superconductivity at 5.7 K and preserved time-reversal symmetry.

Contribution

It provides detailed synthesis and microscopic characterization of a new high entropy alloy superconductor, highlighting its isotropic s-wave pairing and time-reversal symmetry preservation.

Findings

Superconducting transition at 5.7 K confirmed by multiple measurements

Muon spin rotation shows preserved time-reversal symmetry

Superfluid density fits isotropic s-wave model

Abstract

Superconducting high entropy alloy (HEA) are emerging as a new class of superconducting materials. It provides a unique opportunity to understand the complex interplay of disorder and superconductivity. We report the synthesis and detail bulk and microscopic characterization of Nb$_{60}$Re$_{10}$Zr$_{10}$Hf$_{10}$Ti$_{10}$ HEA alloy using transport, magnetization, specific heat, and muon spin rotation/relaxation ($\mu$SR) measurements. Bulk superconductivity with transition temperature $T_{C}$ = 5.7 K confirmed by magnetization, resistivity, and heat capacity measurements. Zero-field $\mu$SR measurement shows that the superconducting state preserves time-reversal symmetry, and transverse-field measurements of the superfluid density are well described by an isotropic s-wave model.