Paramagnetic Electronic Structure of CrSBr: Comparison between Ab Initio GW Theory and Angle-Resolved Photoemission Spectroscopy

TL;DR

This study combines advanced ab initio GW calculations with photoemission experiments to analyze the electronic structure of paramagnetic CrSBr, revealing insights into band broadening, magnetic order effects, and temperature-dependent band gaps.

Contribution

It demonstrates the effectiveness of quasiparticle self-consistent GW methods in accurately modeling the electronic structure of paramagnetic layered materials and compares these with experimental data.

Findings

Excellent agreement between GW calculations and photoemission data at 200 K.

Broadening of bands attributed to broken magnetic order and electronic dispersion.

Experimental band gap at 200 K is at least 1.51 eV; calculated gap is about 2.1 eV.

Abstract

We explore the electronic structure of paramagnetic CrSBr by comparative first principles calculations and angle-resolved photoemission spectroscopy. We theoretically approximate the paramagnetic phase using a supercell hosting spin configurations with broken long-range order and applying quasiparticle self-consistent $GW$ theory, without and with the inclusion of excitonic vertex corrections to the screened Coulomb interaction (QS$GW$ and QS$G\hat{W}$, respectively). Comparing the quasi-particle band structure calculations to angle-resolved photoemission data collected at 200 K results in excellent agreement. This allows us to qualitatively explain the significant broadening of some bands as arising from the broken magnetic long-range order and/or electronic dispersion perpendicular to the quasi two-dimensional layers of the crystal structure. The experimental band gap at 200 K is found to be at least 1.51 eV at 200 K. At lower temperature, no photoemission data can be collected as a result of charging effects, pointing towards a significantly larger gap, which is consistent with the calculated band gap of $\approx$ 2.1 eV.