Local distortions of the crystal structure and their influence on the electronic structure and superconductivity of the high-entropy alloy (TaNb)0.67(HfZrTi)0.33

Local distortions of the crystal structure and their influence on the electronic structure, electronphonon interaction, and superconductivity are theoretically studied in the superconducting high-entropy alloy (TaNb)0.67(HfZrTi)0.33. Distortions of the crystal lattice are caused by the relaxation of atomic positions and are studied in the twelve models of supercells. The largest relative changes in the interatomic distances due to relaxation reach 8%. On average, local distortions tend to lower the density of states at the Fermi level and significantly reduce the electron-phonon coupling parameter lambda. As a result, the calculated superconducting critical temperature is reduced to about 50% of the initial value, which shows the strong impact of structural disorder on superconductivity in this prototype high-entropy alloy. With the reduced value of lambda, the theoretical Tc is closer to the experiment for typical values of the Coulomb pseudopotential parameter mu*. The experimental Tc can be reproduced by taking a slightly enhanced mu* = 0.176, which leaves little room for the possibility of suppression of superconductivity by disorder.