Superconductivity in HEA-type compounds

TL;DR

This paper reviews the development, synthesis, structural variations, and superconducting properties of high-entropy alloy (HEA)-type compounds, highlighting their potential in advancing superconductor science since 2014.

Contribution

It provides a comprehensive summary of HEA-type compounds as superconductors, including synthesis methods, structural diversity, and effects of alloying on superconductivity.

Findings

HEA-type compounds exhibit diverse crystal structures.

Introduction of HEA sites influences superconducting properties.

Various HEA compounds show potential for high-temperature superconductivity.

Abstract

Since the discovery of superconductivity in a high-entropy alloy (HEA) Ti-Zr-Nb-Hf-Ta in 2014, the community of superconductor science has explored new HEA superconductors to find the merit of the HEA states on superconducting properties. Since 2018, we have developed HEA-type compounds as superconductors or thermoelectric materials. As well known, compounds like intermetallic compounds or layered compounds are composed of multi crystallographic sites. In a HEA-type compounds, one or more sites are alloyed and total mixing entropy satisfies with the criterion of HEA. Herein, we summarize the synthesis methods, the crystal structural variation and superconducting properties of the HEA-type compounds, which include NaCl-type metal tellurides, CuAl2-type transition metal zirconides, high-Tc cuprates, and BiS2-based layered superconductors. The effects of the introduction of a HEA site in various kinds of complicated compounds are discussed from the structural-dimensionality viewpoint.