Cutting edge of high-entropy alloy superconductors from the perspective of materials research

TL;DR

This review discusses recent advances in high-entropy alloy superconductors, highlighting new material structures, design strategies, and the potential for discovering novel phenomena in this rapidly evolving field.

Contribution

It provides a comprehensive update on HEA superconductors, including simple and multi-site structures, and introduces new perspectives on eutectic and gum metal HEA superconductors.

Findings

Survey of bcc and hcp HEA superconductors

Discussion of multi-site HEA superconductors with various structures

Introduction of new perspectives on eutectic and gum metal HEA superconductors

Abstract

High-entropy alloys (HEAs) are a new class of materials which are being energetically studied around the world. HEAs are characterized by a multi-component alloy in which five or more elements randomly occupy a crystallographic site. The conventional HEA concept has developed into simple crystal structures such as face-centered-cubic (fcc), body-centered-cubic (bcc) and hexagonal-closed packing (hcp) structures. The highly atomic-disordered state produces many superior mechanical or thermal properties. Superconductivity has been one of the topics of focus in the field of HEAs since the discovery of the bcc HEA superconductor in 2014. A characteristic of superconductivity is robustness against atomic disorder or extremely high pressure. The materials research on HEA superconductors has just begun, and there are open possibilities for unexpectedly finding new phenomena. The present review updates the research status of HEA superconductors. We survey bcc and hcp HEA superconductors and discuss the simple material design. The concept of HEA is extended to materials possessing multiple crystallographic sites; thus, we also introduce multi-site HEA superconductors with the CsCl-type, {\alpha}-Mn-type, A15, NaCl-type, {\sigma}-phase and layered structures and discuss the materials research on multi-site HEA superconductors. Finally, we present the new perspectives of eutectic HEA superconductors and gum metal HEA superconductors.