Ferrovalleytricity in 2D multiferroic lattice with self-doped valley carriers

Abstract

Realizing electrical control of the anomalous valley Hall effect (AVHE) and efficient generation of valley carriers are two fundamental challenges in valleytronics research. Here, we propose a ferroelectric-switching paradigm that enables reversible valley polarization control and spontaneous self-doping of valley carriers in multiferroic van der Waals homobilayers. It is revealed that antiparallel ferroelectric polarization alignment can induce degenerate valley extrema and a semiconducting character, suppressing the AVHE. Conversely, parallel polarization alignment can generate self-doped valley carriers with spin polarization, achieving a spontaneous AVHE. Crucially, reversing the polarization inverts the spin texture while preserving the band character, flipping the sign of the Berry curvatures and thereby reversing the AVHE conductivity. Through first-principles calculations, we demonstrate this mechanism in the ReIrGe2S6 homobilayer. Electrically controlled ferrovalleytricity with self-doped valley carriers offers a promising pathway for non-volatile and energy-efficient valleytronic devices.