Effect of spin-dependent tunneling in a MoSe$_2$/Cr$_2$Ge$_2$Te$_6$ van der Waals heterostructure on exciton and trion emission

TL;DR

This study investigates how spin-dependent tunneling in a MoSe₂/Cr₂Ge₂Te₆ heterostructure influences exciton and trion emissions, revealing ultrafast charge transfer processes affected by magnetic orientation.

Contribution

It demonstrates the impact of spin-dependent tunneling on exciton-trion dynamics in a novel van der Waals heterostructure, highlighting the role of magnetic orientation in charge transfer.

Findings

Exciton-trion emission ratio changes in heterostructure

Emission ratio depends on magnetic orientation

Ultrafast spin-dependent charge transfer occurs

Abstract

We study van der Waals heterostructures consisting of monolayer MoSe$_2$ and few-layer Cr$_2$Ge$_2$Te$_6$ fully encapsulated in hexagonal Boron Nitride using low-temperature photoluminescence and polar magneto-optic Kerr effect measurements. Photoluminescence characterization reveals a partial quenching and a change of the exciton-trion emission ratio in the heterostructure as compared to the isolated MoSe$_2$ monolayer. Under circularly polarized excitation, we find that the exciton-trion emission ratio depends on the relative orientation of excitation helicity and Cr$_2$Ge$_2$Te$_6$ magnetization, even though the photoluminescence emission itself is unpolarized. This observation hints at an ultrafast, spin-dependent interlayer charge transfer that competes with exciton and trion formation and recombination.