Proximity to Fermi-surface topological change in superconducting LaO0.54F0.46BiS2

TL;DR

This study uses ARPES to analyze the electronic structure of LaO$_{0.54}$F$_{0.46}$BiS$_2$, revealing its proximity to a topological change in the Fermi surface that could influence its superconducting properties.

Contribution

The paper provides experimental evidence of the Fermi surface nearing a topological change in a superconducting BiS$_2$-based compound, supported by ARPES and first principles calculations.

Findings

Observation of band dispersions consistent with calculations including spin-orbit coupling.

Detection of a square-like Fermi surface distribution near the Fermi level.

Proximity of the Fermi surface to a predicted topological change.

Abstract

The electronic structure of nearly optimally-doped novel superconductor LaO$_{1-x}$F$_x$BiS$_2$ (${\it x}$ = 0.46) was investigated using angle-resolved photoemission spectroscopy (ARPES). We clearly observed band dispersions from 2 to 6 eV binding energy and near the Fermi level (${\it E}_{\rm F}$), which are well reproduced by first principles calculations when the spin-orbit coupling is taken into account. The ARPES intensity map near ${\it E}_{\rm F}$ shows a square-like distribution around the $\Gamma$(Z) point in addition to electronlike Fermi surface (FS) sheets around the X(R) point, indicating that FS of LaO$_{0.54}$F$_{0.46}$BiS$_2$ is in close proximity to the theoretically-predicted topological change.