High-entropy alloy superconductors on an α-Mn lattice

Abstract

Previously unreported High-Entropy Alloys (HEAs) in the pentanary (ZrNb)_1−x[MoReRu]_x, (HfTaWIr)_1−x[Re]_x, and (HfTaWPt)_1−x[Re]_x systems are described and characterized. The materials have body-centered cubic α-Mn-type structures and mixed site occupancies; a small stoichiometry range is observed for all, and the mixed 4d–5d system has less Re than is typically encountered for Re-containing materials with this structure type. The latter two systems are the first reported 5d-element-only superconducting HEAs. All are type-II bulk superconductors with strongly varying critical temperatures (T_cs) depending on the cubic lattice parameter a and the valence electron count (VEC); the T_cs increase linearly with decreasing a and increasing VEC within each series and fall between the trend lines found for crystalline and amorphous transition metal alloy superconductors.