Superconductivity of Ta34Nb33Hf8Zr14Ti11 high entropy alloy from first principles calculations

TL;DR

This study uses first-principles calculations to analyze the superconducting properties of a high entropy alloy, estimating electron-phonon coupling and confirming strong coupling consistent with experimental data.

Contribution

It provides the first theoretical estimation of electron-phonon coupling in the superconducting high entropy alloy Ta34Nb33Hf8Zr14Ti11 using KKR-CPA methods.

Findings

Estimated electron-phonon coupling constant  = 1.16

Calculated  close to experimental value 0.98

Indicates strong electron-phonon coupling in the alloy

Abstract

The Korringa-Kohn-Rostoker method with the coherent potental approximation (KKR-CPA) is applied to study the first superconducting high entropy alloy (HEA) Ta34Nb33Hf8Zr14Ti11 (discovered in 2014 with Tc = 7.3 K), focusing on estimations of the electron-phonon coupling constant \lambda. Electronic part of \lambda has been calculated using the rigid muffin-tin approximation (RMTA), while the phonon part has been approximated using average atomic mass and experimental Debye temperature. The estimated \lambda = 1.16 is close to the value determined from specific heat measurements, \lambda = 0.98, and suggests rather strong electron-phonon coupling in this material.