Polarization-Field-Driven Asymmetric Magnetoelectric Coupling in Janus MoSeS-Based van der Waals Heterostructures.

Modulating interfacial magnetoelectric coupling is a crucial means of tuning physical properties in heterostructures for next-generation spintronic devices. This work reports a strategy to directly modulate such coupling in van der Waals semiconductor/ferromagnetic heterostructures via built-in polarization electric fields. By constructing Janus MoSeS/CrBr3 and MoSSe/CrBr3 heterostructures with opposite polarization directions, combined with spectroscopic measurements and theoretical calculations, we reveal the polarization-electric-dependent modulation mechanism. The polarization field tunes the electronic structure and interlayer charge transport in the heterostructures, thereby altering the magnetoelectric coupling strength and spin-valley properties. In the MoSeS/CrBr3 heterostructure, it markedly enhances interfacial orbital hybridization, enabling ultrafast selective spin-charge tunneling, shortening the exciton lifetime, and boosting the valley polarization in MoSeS. In contrast, in the MoSSe/CrBr3 heterostructure, it strengthens the interlayer magnetoelectric coupling, inducing a large conduction band valley splitting in MoSSe, but interlayer charge transfer is dominated by a slower drift mechanism, prolonging the exciton lifetime and leading to a lower valley polarization. This work provides insights into polarization-field-modulated magnetoelectric coupling and offers additional insights for the design of advanced valleytronic devices.