Investigating the effect of temperature dependent many-body interactions on bulk electronic structures and the robust nature of (001) surface states of SnTe

TL;DR

This study investigates how temperature-dependent many-body interactions influence the electronic structure and surface state robustness of SnTe, combining DFT and GW methods to reveal temperature effects on bandgaps and surface state protection.

Contribution

It provides a comprehensive analysis of temperature effects on SnTe's electronic structure using advanced many-body techniques, highlighting the role of EEI and surface state robustness.

Findings

Bandgap at 300K is approximately 161 meV.

Temperature-dependent EEI reduces the bandgap with increasing temperature.

(001) surface states are robust against defects due to symmetry protections.

Abstract

Recently, SnTe has gained attention due to its non-trivial topological nature and eco-friendly thermoelectric applications. We report a detailed temperature dependent electronic structure and thermodynamic properties of this compound using DFT and GW methods. The calculated values of bandgaps by using PBEsol and $G_0W_0$ methods are found to be in good agreement with the experiment, whereas mBJ underestimates the bandgap. The estimated value of fully screened Coulomb interaction ($W$) for Sn (Te) 5$p$ orbitals is $\sim$1.39 ($\sim$1.70) eV. The nature of frequency dependent $W$ reveals that the correlation strength of this compound is relatively weaker and hence the excited electronic state can be properly studied by full-$GW$ many-body technique. The plasmon excitation is found to be important in understanding this frequency dependent $W$. In order to describe the experimental phonon modes, the long range Coulomb forces using nonanalytical term correction is considered. The temperature dependent electron-electron interactions (EEI) reduces the bandgaps with increasing temperature. The value of bandgap at 300 K is obtained to be $\sim$161 meV. The temperature dependent lifetimes of electronic state along W-L-$\Gamma$ direction are also estimated. This work suggests that EEI is important to explain the high temperature transport behaviour of SnTe. We have also explored the possibility of protecting the (001) surface states via mirror and time-reversal symmetry. These surface states are expected to be robust against the point and line defects.