Ferroelectric tuning of the valley polarized metal-semiconductor transition in Mn2 P2 S3Se3 / Sc2CO2 van der Waals heterostructures and application to nonlinear Hall effect devices

To promote the development of the next generation of nanospintronic devices, it is of great significance to tune the valley degree of freedom in two-dimensional (2D) materials. Here, we propose a mechanism for manipulating the valley and nonlinear Hall effect using a 2D ferroelectric substrate. Monolayer Mn2P2S3Se3 is a robust antiferromagnetic, valley polarized semiconductor. Importantly, the valley polarized metal-semiconductor phase transition of Mn2P2S3Se3 can be effectively tuned by switching the ferroelectric polarization of Sc2CO2. We reveal the microscopic mechanism of the phase transition, which originates from charge transfer and band alignment. Additionally, we find that the reversed polarization direction of Sc2CO2 can flexibly manipulate the Berry curvature dipole. Based on this discovery, we present the detection of the valley polarized metal-semiconductor transition using nonlinear Hall effect devices. These findings not only offer a scheme to tune the valley degree of freedom but also provide a promising platform for designing nonlinear Hall effect devices.