Semiconducting ferromagnet-nonmagnet interfaces in van der Waals heterostructures present a unique opportunity to investigate magnetic proximity interactions dependent upon a multitude of phenomena including valley and layer pseudospins, moir\'e periodicity, or exceptionally strong Coulomb binding. Here, we report a charge-state dependency of the magnetic proximity effects between MoSe2 and CrBr3 in photoluminescence, whereby the valley polarization of the MoSe2 trion state conforms closely to the local CrBr3 magnetization, while the neutral exciton state remains insensitive to the ferromagnet. We attribute this to spin-dependent interlayer charge transfer occurring on timescales between the exciton and trion radiative lifetimes. Going further, we uncover by both the magneto-optical Kerr effect and photoluminescence a domain-like spatial topography of contrasting valley polarization, which we infer to be labyrinthine or otherwise highly intricate, with features smaller than 400 nm corresponding to our optical resolution. Our findings offer a unique insight into the interplay between short-lived valley excitons and spin-dependent interlayer tunnelling, while also highlighting MoSe2 as a promising candidate to optically interface with exotic spin textures in van der Waals structures.
@article{arxiv.2004.04073,
title = {Interplay between spin proximity effect and charge-dependent exciton dynamics in MoSe$_2$ / CrBr$_3$ van der Waals heterostructures},
author = {T. P. Lyons and D. Gillard and A. Molina-Sánchez and A. Misra and F. Withers and P. S. Keatley and A. Kozikov and T. Taniguchi and K. Watanabe and K. S. Novoselov and J. Fernández-Rossier and A. I. Tartakovskii},
journal= {arXiv preprint arXiv:2004.04073},
year = {2021}
}