Ferroelectric Spin-Valley Coupling in van der Waals Bilayers

Sliding ferroelectricity, where the out-of-plane electric polarization is switched by in-plane interlayer sliding, has been recently proposed and confirmed in numerous stacked two-dimensional van der Waals (vdW) bilayers [1-4]. This unusual ferroelectricity has sparked a great deal of interest, as it not only paves the new way for the realization of vdW ferroelectric devices, but also introduces exciting new elements to spintronics and valleytronics via ferroelectric spin-valley coupling [1]. Here, by using a low-energy effective model and first-principles calculations, we demonstrate how the sliding ferroelectricity induces spin-valley polarizations and anomalous Hall effects in vdW bilayers. Through the analysis of topology, we also illustrate the mechanism and realization of magnetic topological states using strain. Our research offers a fresh perspective to understand and manipulate the interaction between electron charge, spin, and valley degrees of freedom.