Paramagnetic electronic structure of CrSBr: Comparison between ab initio GW theory and angle-resolved photoemission spectroscopy

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 (QSGW and QSGW, respectively). Comparing the quasiparticle 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 approximately 2.1 eV.

Automated summary

We investigate the electronic structure of paramagnetic CrSBr through first-principles calculations and angle-resolved photoemission spectroscopy. By using a supercell approximation and quasiparticle self-consistent GW theory with excitonic vertex corrections, we calculate the paramagnetic phase with broken long-range order. Comparing the calculated quasiparticle band structure with experimental photoemission data at 200 K shows excellent agreement, allowing us to explain the broadening of some bands due to broken magnetic order and/or electronic dispersion perpendicular to the quasi-two-dimensional layers. The experimental band gap at 200 K is found to be at least 1.51 eV, while calculations suggest a larger gap of approximately 2.1 eV at lower temperature.