Interplay between charge transfer and magnetic proximity effects in WSe/CrCl heterostructures.

Ferromagnetism in van der Waals systems with diverse spin arrangements opened a pathway to use proximity magnetic fields to activate the properties of materials that would otherwise require external stimuli. Herein, we demonstrate this concept by creating heterostructures comprising a bulk CrCl antiferromagnet with in-plane easy-axis magnetization and a monolayer (ML) WSe semiconductor. Photoluminescence and magnetic force microscopy techniques were performed to reveal the interaction between the relevant layers in the WSe/CrCl heterostructures (HSs). The quenching of the WSe emission is apparent in the WSe/CrCl HSs due to an efficient charge transfer process enabled by the relative band alignment within the structures. Moreover, we demonstrate that at specific spatial locations in the structures, the magnetic proximity effect between the WSe ML and the CrCl bulk activates dark exciton emission within the WSe ML. The dark exciton emission in the WSe ML survives to a higher temperature than the intraplane Curie temperature () of the CrCl because of its elevated in the strained regions of the CrCl layer. Our findings are relevant to the development of spintronics and valleytronics with long-lived dark states on technological timescales, as well as to sensing applications of local magnetic fields realized simultaneously in multiple dimensions.