Fluorine solubility and superconducting properties of Sm(O,F)BiS$_2$ single crystals

TL;DR

This study investigates the fluorine solubility limits and superconducting properties of Sm(O,F)BiS2 single crystals, revealing an intrinsic phase stability and the relationship between fluorine content and superconducting transition temperature.

Contribution

It provides new insights into the fluorine solubility limit and superconducting behavior of Sm(O,F)BiS2 single crystals, highlighting the intrinsic phase stability and effects of fluorine doping.

Findings

Fluorine solubility limit is approximately less than 20 at%.

Superconductivity appears around 5 K in the crystals.

Superconducting transition temperature increases with nominal F content below 70 at%.

Abstract

Sm(O,F)BiS2 superconducting single crystals with various nominal F contents have been grown using KI-KCl flux. The solid solution limit of F at the O-site in Sm(O,F)BiS2 single crystals was approximately less than 20 at%. F concentrations of Sm(O,F)BiS2 single crystals were hardly controlled by nominal F contents. It suggests the existence of intrinsic stable phase. Superconductivity was shown at around 5 K. Superconducting transition temperature with zero resistivity were increased with increasing nominal F contents within less than 70 at% in O-site, despite similar F concentration and c-axis lattice constants.