Large exciton binding energies in MnPS$_3$ as a case study of vdW layered magnet

TL;DR

This study predicts that antiferromagnetic MnPS$_3$ monolayers have giant excitonic binding energies over 1 eV, surpassing TMDCs, and can be used for magneto-optical and optospintronics applications.

Contribution

It demonstrates, through first principles calculations, that MnPS$_3$ monolayers exhibit exceptionally large exciton binding energies and offers methods to infer magnetic ordering via optical polarization.

Findings

Excitons in MnPS$_3$ are bound by over 1 eV.

Giant excitonic binding energies are predicted in MPX$_3$ monolayers.

Magnetic ordering can be inferred from light polarization.

Abstract

Stable excitons in semiconductor monolayers such as transition-metal dichalcogenides (TMDCs) enable and motivate fundamental research as well as the development of room-temperature optoelectronics applications. The newly discovered layered magnetic materials present a unique opportunity to integrate optical functionalities with magnetism. We predict that a large class of antiferromagnetic semiconducting monolayers of the MPX$_3$ family exhibit giant excitonic binding energies, making them suitable platforms for magneto-optical investigations and optospintronics applications. Indeed, our investigations, based on first principles methods combined with an effective-model Bethe-Salpeter solver, show that excitons in bare Neel-MnPS$_3$ are bound by more than 1 eV, which is twice the excitonic energies in TMDCs. In addition, the antiferromagnetic ordering of monolayer samples can be inferred indirectly using different polarization of light.