Multidimensional sensing of proximity magnetic fields via intrinsic activation of dark excitons in WSe${}_2$/CrCl${}_3$ heterostructure

Abstract

Quantum phenomena at interfaces create functionalities at the level of materials. Ferromagnetism in van der Waals systems with diverse arrangements of spins opened a pathway for utilizing proximity magnetic fields to activate properties of materials which would otherwise require external stimuli. Herewith, we realize this notion via creating heterostructures comprising bulk CrCl${}_3$ ferromagnet with in-plane easy-axis magnetization and monolayer WSe${}_2$ semiconductor. We demonstrate that the in-plane component of the proximity field activates the dark excitons within WSe${}_2$. Zero-external-field emission from the dark states allowed us to establish the in-plane and out-of-plane components of the proximity field via inspection of the emission intensity and Zeeman effect, yielding canted orientations at the degree range of $10^{\circ }$ $-$ $30^{\circ }$ at different locations of the heterostructures, attributed to the features of interfacial topography. Our findings are relevant for the development of spintronics and valleytronics with long-lived dark states in technological timescales and sensing applications of local magnetic fields realized simultaneously in multiple dimensions.

7 pages, 5 figures + SI

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