Microscopic study of equiatomic high entropy alloy superconductors using µSR measurement

Recently, high entropy alloys (HEAs) have garnered significant attention as an unconventional class of alloys due to their unique composition, marked by a mixture of multiple elements in significant proportions. The stability of these alloys is attributed to the substantial alteration in configurational entropy during their synthesis, resulting in a high degree of chemical disorder. However, despite this disorder, they share simple crystal structures akin to pure metals, including bcc, hcp, and fcc. High entropy alloys provide a versatile platform for tailoring superconducting properties through precise adjustments in composition and crystal structure. Their unique feature of lacking regular phonon modes, which are critical for conventional BCS superconductivity, makes them excellent candidates for exploring unconventional pairing mechanisms. Substantial efforts have been invested in the quest for new HEA superconductors with various crystal structures and in fine-tuning their transition temperatures by incorporating 3d, 4d, and 5d elements. This proposal seeks to thoroughly examine the microscopic properties of the equiatomic HEA family XTiVNb, where X is ScHf, CrTa, and MoW. In this family of materials the variation from 3d to 5d elements will result in significant spin-orbit coupling effects, and irregular phonon modes may provide the basis for a non-BCS pairing mechanism.