Unlocking reversible and nonvolatile anomalous valley Hall control through multiferroic van der Waals heterostructures

Achieving external control over the anomalous valley Hall (AVH) effect is essential for advancing valleytronic applications. However, many of the existing approaches suffer from limitations such as irreversibility or volatility. In this work, we propose a general strategy for enabling nonvolatile electrical tuning of the AVH effect by utilizing multiferroic van der Waals heterostructures. Using first-principles density functional theory calculations, we demonstrate that a heterostructure composed of a ferromagnetic monolayer VSSe and a ferroelectric monolayer Al$_2$S$_3$ permits fine control of valley transport properties. The AVH response in VSSe can be reversibly and nonvolatility switched by reversing the polarization of Al$_2$S$_3$ via an applied electric field. This ferroelectric mechanism ensures a stable valley state even without continuous energy input. Furthermore, the valley polarization can also be inverted through the same polarization switching process, providing a dual degree of control over valley-dependent phenomena. These findings establish a promising pathway toward intrinsically switchable and energy-efficient valleytronic devices.