Superconductivity in BiS₂-based layered compound REO_0.5F_0.5BiS₂ with high-entropy-alloy-type (HEA-type) blocking layers

We have synthesized BiS₂-based superconductors with high-entropy-alloy-type (HEA-type) REO (RE: rare earth) blocking layers [R. Sogabe et al., APEX 2018]. In the HEA-type samples, the RE site of REO_0.5F_0.5BiS₂ was occupied with five RE elements with a compositional range of 5–35%. Notably, the superconducting properties were enhanced by making HEA-type REO blocking layer as compared to the BiS₂-based superconductors with a conventional REO blocking layer. We will discuss about the interlayer interaction in the HEA-type REO_0.5F_0.5BiS₂ superconductors by examining the samples having similar lattice parameters and different mixing entropy for the RE site. [R. Sogabe et al., 1808.04090]