Dual-Switch Control of a Layer-Locked Anomalous Valley Hall Effect in a Sliding Ferroelectric Antiferromagnet

TL;DR

This paper demonstrates a dual-switch mechanism in bilayer VS2, enabling electrical and magnetic control of valley Hall effects in a 2D multiferroic material, advancing spin-valleytronics technology.

Contribution

It introduces a novel dual-switching approach in a room-temperature FE-AFM 2D material, allowing independent and reversible control of valley states via electric and magnetic stimuli.

Findings

Interlayer sliding induces switchable ferroelectric polarization.

Reversible switching of valley polarization by electric and magnetic means.

Electric and magnetic controls are functionally equivalent for valley manipulation.

Abstract

The integration of ferroelectric (FE) and antiferromagnetic (AFM) orders in twodimensional (2D) materials provides a promising avenue for the nonvolatile control of coupled spin and valley degrees of freedom, a capability central to advancing spinvalleytronics. However, realizing a single material system where these quantum states can be independently and reversibly manipulated by distinct stimuli, a prerequisite for multifunctional devices, has remained elusive. Here, we demonstrate a dual-switch mechanism in bilayer VS2, a room-temperature FE-AFM system, that enables electrical and magnetic control of a layer-locked anomalous valley Hall effect (AVHE). First-principles calculations reveal that interlayer sliding breaks spatial inversion symmetry, inducing a switchable out-of-plane FE polarization that coexists with interlayer AFM. The spin-orbit coupled valley polarization can be reversibly switched either by FE polarization reversal or by a magnetic-field-induced spin-flip transition, confirming the existence of electrically and magnetically addressable valley states. The Berry curvature exhibits both valley-contrasting and layer-locked characteristics, which underpin a switchable Hall response. Notably, electric and magnetic switching are functionally equivalent in modulating valley, layer, and spin indices, revealing strong magnetoelectric coupling. This work establishes a multidegree-of-freedom operational paradigm in 2D multiferroics and opens a viable design pathway toward multi-state memory and spin-valleytronic logic devices.