Normal state electronic properties of LaO$_{1-x}$F$_{x}$BiS$_{2}$ superconductors

TL;DR

This paper models the normal state electronic structure of LaO$_{1-x}$F$_{x}$BiS$_{2}$ superconductors using a minimal microscopic approach, incorporating moderate electron correlations to better match experimental ARPES data.

Contribution

It introduces a simplified microscopic model with electron correlations to accurately describe the low-energy electronic properties of LaO$_{1-x}$F$_{x}$BiS$_{2}$, aligning with experimental observations.

Findings

Moderate electron correlations improve agreement with ARPES data.

Predicted temperature dependence of spectral features at various Brillouin zone points.

Calculated spectral density around the conduction band minimum.

Abstract

A good description of the electronic structure of BiS$_{2}$-based superconductors is essential to understand their phase diagram, normal state and superconducting properties. To describe the first reports of normal state electronic structure features from angle resolved photoemission spectroscopy (ARPES) in LaO$_{1-x}$F$_{x}$BiS$_{2}$, we used a minimal microscopic model to study their low energy properties. It includes the two effective tight-binding bands proposed by Usui et al [Phys.Rev.B 86, 220501(R)(2012)], and we added moderate intra- and inter-orbital electron correlations related to Bi-($p_{Y}$, $p_{X}$) and S-($p_{Y}$, $p_{X}$) orbitals. We calculated the electron Green's functions using their equations of motion, which we decoupled in second-order of perturbations on the correlations. We determined the normal state spectral density function and total density of states for LaO$_{1-x}$F$_{x}$BiS$_{2}$, focusing on the description of the k-dependence, effect of doping, and the prediction of the temperature dependence of spectral properties. Including moderate electron correlations, improves the description of the few experimental ARPES and soft X-ray photoemission data available for LaO$_{1-x}$F$_{x}$BiS$_{2}$. Our analytical approximation enabled us to calculate the spectral density around the conduction band minimum at $\vec{k}_{0}=(0.45\pi,0.45\pi)$, and to predict the temperature dependence of the spectral properties at different BZ points, which might be verified by temperature dependent ARPES.