Proximity-Induced Exchange Interaction and Prolonged Valley Lifetime in MoSe₂/CrSBr Van-Der-Waals Heterostructure with Orthogonal Spin Textures

Heterostructures, composed of semiconducting transition-metal dichalcogenides (TMDC) and magnetic van-der-Waals materials, offer exciting prospects for the manipulation of the TMDC valley properties via proximity interaction with the magnetic material. We show that the atomic proximity of monolayer MoSe₂ and the antiferromagnetic van-der-Waals crystal CrSBr leads to an unexpected breaking of time-reversal symmetry, with originally perpendicular spin directions in both materials. The observed effect can be traced back to a proximity-induced exchange interaction via first-principles calculations. The resulting spin splitting in MoSe₂ is determined experimentally and theoretically to be on the order of a few meV. Moreover, we find a more than 2 orders of magnitude longer valley lifetime of spin-polarized charge carriers in the heterostructure, as compared to monolayer MoSe₂/SiO₂, driven by a Mott transition in the type-III band-aligned heterostructure.