Electronic Band Structures and Excitonic Properties of Delafossites: A $\textit{GW}$-BSE study

TL;DR

This study uses advanced GW-BSE calculations to analyze the electronic and excitonic properties of delafossites, revealing their indirect band gaps and significant exciton binding energies, with results aligning well with experimental data.

Contribution

First comprehensive GW-BSE analysis of delafossites' band structures and excitonic properties, highlighting their indirect gaps and strong excitons.

Findings

All delafossites are indirect band gap semiconductors.

Exciton binding energies range from 0.24 to 0.44 eV.

The lowest excitons are located at the L point of the Brillouin zone.

Abstract

We report the band structures and excitonic properties of delafossites $CuMO_2$ (M = Al, Ga, In, Sc, Y, Cr) calculated using the state-of-the-art $\textit{GW}$-BSE approach. We find that all the delafossites are indirect band gap semiconductors with large exciton binding energies, varying from 0.24 to 0.44 eV. The lowest and strongest exciton, mainly contributed from either Cu 3$\textit{d}$ $\rightarrow$ Cu 3$\textit{p}$ (Al, Ga, In) or Cu 3$\textit{d}$ $\rightarrow$ M 3$\textit{d}$ (M = Sc, Y, Cr) transitions, is always located at $L$ point of the rhombohedral Brillouin zone. Taking the electron-hole effect into account, our theoretical band gaps exhibit nice agreement with experiments.