Influence of nanostructuring through high-pressure torsion (HPT) on superconductivity of a high-entropy alloy

TL;DR

This study demonstrates that nanostructuring high-entropy alloys via high-pressure torsion enhances their superconducting properties by microstructural modifications, including grain refinement and phase transformation, leading to increased transition temperature and critical magnetic field.

Contribution

It introduces a novel approach of using high-pressure torsion to improve superconductivity in high-entropy alloys through controlled nanostructuring.

Findings

Superconducting transition temperature increased from 6.2 K to 7.2 K.

Critical magnetic field was enhanced after HPT processing.

Microstructural changes correlate with improved superconducting properties.

Abstract

High-entropy alloys (HEAs) have emerged as favorable choices for different applications, including superconductors. The present work examines the impact of nanostructuring via high-pressure torsion (HPT) on the superconducting properties of the equiatomic TiZrHfNbTa HEA. Structural characterization reveals a progressive refinement of grain size and increased dislocation density, together with partial phase transformation to an {\omega} phase with HPT processing. Magnetic susceptibility and magnetization measurements indicate a systematic enhancement in the superconducting transition temperature (from $T_c =$ 6.2 K to 7.2 K) and critical magnetic field, as well as the stabilization of the superconductivity state by HPT processing. The improvement of superconducting properties is attributed to microstructural modifications such as grain boundary density, defect generation and phase transformations, and their impact on vortex pinning, quantum confinement and electron scattering. The results suggest that nanostructuring through severe plastic deformation provides an appropriate route to optimize superconducting properties in high-entropy superconductors.