Giant Nonequilibrium Valley Control via Spin‐Selective Hot‐Carrier Transfer in an Antiferromagnetic van der Waals Stack

ABSTRACT

Spin‐selective hot‐carrier transfer at interfaces between two‐dimensional (2D) semiconductors and magnets offers a nonequilibrium route to manipulate spin and valley degrees of freedom. In van der Waals heterostructures, such transfer can be enabled by type‐III band alignment together with magnetic‐field‐induced spin polarization of the bands in adjacent magnetic layers. Yet, continuous and robust valley control with high magnetic‐field susceptibility remains challenging, particularly beyond binary switching in out‐of‐plane easy‐axis magnets. Here we fabricate a CrSBr/WSe ₂ /CrSBr heterostructure, where two semiconductor‐magnet interfaces promote efficient hot‐carrier transfer. Utilizing valley‐resolved magneto‐photoluminescence spectroscopy, we reveal a pronounced field‐sign‐asymmetric response and a magnetic‐state‐dependent evolution of emergent spectral features that track the spin configuration of multilayer CrSBr via spin‐selective hot‐carrier transfer. This mechanism enables giant, continuous tuning, and magnetic‐state‐dependent reversal of the degree of circular polarization (DoCP), reaching ∼ 40% for excitons and ∼ 80% for trion emission. Our results establish spin‐polarized interlayer hot‐carrier transfer as an efficient knob for engineering valley polarization and coherence in TMDs, and highlight antiferromagnet‐based stacks as a versatile platform for magnetically programmable quantum optoelectronic functionalities.