Spin dependent charge transfer in MoSe₂/hBN/Ni hybrid structures

The manipulation of the spin/valley properties in monolayer transition metal dichalcogenide (TMD) monolayers (MLs) can be achieved thanks to a magnetic layer in close proximity to the TMD ML. We present magneto-photoluminescence measurements in a hybrid 2D semiconductor/ ferromagnetic structure consisting of MoSe₂/hBN/Ni. When the Nickel layer is magnetized, we observe circularly polarized photoluminescence of the trion peak in MoSe₂ monolayer under linearly polarized excitation. This build-up of circular polarization can reach a measured value of about 4% when the magnetization of Ni is saturated perpendicularly to the sample plane, and changes its sign when the magnetization is reversed. The circular polarization decreases when the hBN barrier thickness increases. These results are interpreted in terms of a spin-dependent charge transfer between the MoSe₂ monolayer and the Nickel film. The build-up of circular polarization is observed up to 120 K, mainly limited by the trion emission that vanishes with temperature.