Evolution of superconductivity in BiS2-based superocnductor LaO0.5F0.5Bi(S1-xSex)2

TL;DR

This study explores how substituting selenium for sulfur in LaO0.5F0.5BiS2 enhances superconductivity, revealing a correlation between lattice expansion, metallic behavior, and increased critical temperature.

Contribution

It provides systematic experimental evidence on how Se substitution induces bulk superconductivity and increases Tc in BiS2-based superconductors.

Findings

Bulk superconductivity appears for x > 0.2

Maximum Tc of 3.8 K at x = 0.5

Superconductivity correlates with metallic conductivity

Abstract

We have systematically investigated the crystal structure, magnetic susceptibility, and electrical resistivity of the BiS2-based superconductor LaO0.5F0.5Bi(S1-xSex)2 (x = 0 - 0.7). With expanding lattice volume by Se substitution, bulk superconductivity was induced for x > 0.2, and the highest Tc of 3.8 K was observed in x = 0.5 (LaO0.5F0.5BiSSe). Metallic conductivity was observed for x > 0.3 in the resistivity measurement, whereas semiconducting-like behavior was observed for x < 0.2. The induction of bulk superconductivity by the partial substitution of S by Se in the LaO0.5F0.5BiS2 superconductor should be positively linked to the enhancement of metallic conductivity.