HEA Effects in Layered Unconventional Superconductors: Cuprates and BiS2-based Superconductors

The high-entropy alloy (HEA) concept was introduced to the RE site (RE: rare earth element) for REBa2Cu3Ox cuprate and REOBiS2 BiS2-based layered superconductorsLayered superconductor. REBa2Cu3Ox single-crystalline whiskers and REOBiS2 single crystalsSingle crystal with HEAs were grown using the flux method. The superconducting properties (superconducting transition temperature: Tc andSuperconducting anisotropy superconducting anisotropy: γs) were little affected by theMixed entropy mixed entropy (ΔSmix) at the RE site. These results were observed using single-crystalline samples. From another perspective, the HEAs concept can be applied to REBa2Cu3Ox and REOBiS2 superconductors without degrading their superconducting properties. However, for the REOBiS2 superconductor, the atomic configuration of the RE site (equivalent or nonequivalent) affected the superconducting properties.