Intrinsic localized excitons in MoSe$_2$/CrSBr heterostructures

TL;DR

This study investigates localized excitons in MoSe₂/CrSBr heterostructures, revealing defect-induced excitons, spin-dependent charge transfer, and anisotropic optical responses, advancing understanding for spintronic and valleytronic applications.

Contribution

It provides the first detailed analysis of defect-related localized excitons and spin-dependent phenomena in MoSe₂/CrSBr heterostructures, combining experimental and theoretical insights.

Findings

Localized exciton X* originates from defects in CrSBr

Opposite valley polarization of X* and trions under magnetic field

CrSBr's anisotropy influences MoSe₂ optical responses

Abstract

We present a comprehensive investigation of optical properties in MoSe$_2$/CrSBr heterostructures, unveiling the presence of localized excitons represented by a new emission feature, X$^*$. We demonstrate through temperature- and power-dependent photoluminescence spectroscopy that X$^*$ originates from excitons confined by intrinsic defects within the CrSBr layer. The valley polarization of X$^*$ and trion peaks displays opposite polarity under a magnetic field, which closely correlates with the magnetic order of CrSBr. This is attributed to spin-dependent charge transfer mechanisms across the heterointerface, supported by density functional theory calculations revealing a type-II band alignment and spin-polarized band structures. Furthermore, the strong in-plane anisotropy of CrSBr induces unique polarization-dependent responses in MoSe$_2$ emissions. Our study highlights the crucial role of defects in shaping excitonic properties. It offers valuable insights into spectral-resolved proximity effects in van der Waals heterostructures between semiconductor and magnet, contributing to advancing spintronic and valleytronic devices.