Charge transfer and asymmetric coupling of MoSe$_2$ valleys to the magnetic order of CrSBr

TL;DR

This study demonstrates how the magnetic order of CrSBr influences the optical and valley properties of monolayer MoSe2 in a vdW heterostructure, revealing charge transfer and asymmetric magnetic proximity effects relevant for opto-spintronics.

Contribution

It provides experimental and theoretical evidence of magnetic order affecting valley and excitonic properties in MoSe2/CrSBr heterostructures, highlighting charge transfer and asymmetric coupling mechanisms.

Findings

Magnetic order of CrSBr alters MoSe2 photoluminescence properties.

Charge transfer occurs facilitated by a broken-gap band alignment.

Asymmetric magnetic proximity effects influence valley g-factors.

Abstract

Van der Waals (vdW) heterostructures composed of two-dimensional (2D) transition metal dichalcogenides (TMD) and vdW magnetic materials offer an intriguing platform to functionalize valley and excitonic properties in non-magnetic TMDs. Here, we report magneto-photoluminescence (PL) investigations of monolayer (ML) MoSe$_2$ on the layered A-type antiferromagnetic (AFM) semiconductor CrSBr under different magnetic field orientations. Our results reveal a clear influence of the CrSBr magnetic order on the optical properties of MoSe$_2$, such as an anomalous linear-polarization dependence, changes of the exciton/trion energies, a magnetic-field dependence of the PL intensities, and a valley $g$-factor with signatures of an asymmetric magnetic proximity interaction. Furthermore, first principles calculations suggest that MoSe$_2$/CrSBr forms a broken-gap (type-III) band alignment, facilitating charge transfer processes. The work establishes that antiferromagnetic-nonmagnetic interfaces can be used to control the valley and excitonic properties of TMDs, relevant for the development of opto-spintronics devices.