Minimum model and its theoretical analysis for superconducting materials with BiS$_2$ layers

TL;DR

This paper investigates the electronic structure of the superconductor LaO$_{1-x}$F$_x$BiS$_2$ using first principles calculations, analyzing how lattice parameters and doping influence the band gap and carrier properties.

Contribution

It introduces a minimal model for the BiS$_2$ layer and provides a theoretical analysis of how structural factors affect electronic properties in this superconductor.

Findings

Band gap depends on La-S distance and fluorine doping.

Lattice structure does not affect the four orbital model of the BiS$_2$ layer.

Light electron doping influences carrier concentration and transport properties.

Abstract

We perform first principles band calculation of the newly discovered superconductor LaO$_{1-x}$F$_x$BiS$_2$, and study the lattice structure and the fluorine doping dependence of the gap between the valence and conduction bands. We find that the distance between La and S as well as the fluorine doping significantly affects the band gap. On the other hand, the four orbital model of the BiS$_2$ layer shows that the lattice structure does not affect this portion of the band. Still, the band gap can affect the carrier concentration in the case of light electron doping, which in turn should affect the transport properties.