Superconductivity in Cubic A15-type V–Nb–Mo–Ir–Pt High-Entropy Alloys

Abstract

We report the crystal structure and superconducting properties of new V5+2xNb35−xMo35−xIr10Pt15 high-entropy alloys (HEAs) for x in the range of 0 ≤x≤ 10. These HEAs are found to crystallize in a cubic A15-type structure and have a weakly coupled, fully gapped superconducting state. A maximum Tc of 5.18 K and zero-temperature upper critical field Bc2(0) of 6.4 T are observed at x = 0, and both quantities decrease monotonically with the increase of V content x. In addition, Tc shows an increase with increasing valence electron concentration from 6.4 to 6.5, which is compared with other A15-type HEA and binary superconductors.

Superconductivity in the bcc‐Type High‐Entropy Alloy TiHfNbTaMo

“…In general, high levels of disorder in crystalline superconductors limit the formation of Cooper pairs, partly due to a decrease in state density or an increase in effective Coulomb repulsion between paired electrons. [ 12,13 ] It has been reported that HEA superconductors exist in bcc‐, [ 2,3,14–22 ] α‐Mn‐, [ 23 ] β‐Mn, [ 24 ] hcp‐, [ 25–27 ] CsCl‐, [ 28,29 ] A15‐type [ 30–32 ] and σ‐phase [ 33,34 ] structures. Additionally, high‐entropy superconductors' superconducting transition temperature ( T c ) are robust against physical pressure and show a certain correlation with valence electron count (VEC).…”