Effect of Electron Count and Chemical Complexity in the Ta-Nb-Hf-Zr-Ti High-Entropy Alloy Superconductor

TL;DR

This study investigates how electron count and chemical complexity influence superconductivity in the Ta-Nb-Hf-Zr-Ti high-entropy alloy, revealing its intermediate behavior between crystalline and amorphous superconductors.

Contribution

It demonstrates the valence-electron count dependence of superconductivity in high-entropy alloys and proposes these alloys as models for studying the evolution of superconductivity.

Findings

Superconducting transition temperature depends on valence-electron count.

High-entropy alloys exhibit properties between crystalline and amorphous superconductors.

Robustness against disorder in high-entropy alloy superconductors.

Abstract

High-entropy alloys are made from random mixtures of principal elements on simple lattices, stabilized by a high mixing entropy. The recently discovered BCC Ta-Nb-Hf-Zr-Ti high entropy alloy superconductor appears to display properties of both simple crystalline intermetallics and amorphous materials, e.g. it has a well defined superconducting transition along with an exceptional robustness against disorder. Here we show that the valence-electron count dependence of the superconducting transition temperature in the high entropy alloy falls between those of analogous simple solid solutions and amorphous materials, and test the effect of alloy complexity on the superconductivity. We propose high-entropy alloys as excellent intermediate systems for studying superconductivity as it evolves between crystalline and amorphous materials.