Multistate ferroelectricity and switchable layer-locked anomalous valley Hall effects in bilayer ReIrGe2Se6
arXiv:2607.14461
The paper predicts, via first‑principles calculations, that bilayer ReIrGe2Se6 exhibits four stable ferroelectric states whose switching controls layer‑locked anomalous valley Hall effects and Berry‑curvature‑driven transport.
Abstract
Two-dimensional multiferroic materials, which combine magnetic and ferroelectric (FE) orders with strong magnetoelectric coupling, represent ideal platforms for high-density information storage and low-power multistate electronics. However, the intrinsic bistability of conventional ferroelectricity poses a substantial challenge to realizing multiple nonvolatile states and programmable Berry-curvature driven transport responses within a single material. Here, using first-principles calculations, we predict multistate ferroelectricity in AA0-stacked bilayer ReIrGe2Se6. The system hosts four energetically stable FE polarization configurations, among which three are connected through reversible switching pathways, while the fourth exhibits a unidirectional switching pathway. The distinct FE configurations further give rise to a cyclic semiconductor-metal-semiconductor evolution in the electronic structure. Notably, FE polarization switching is intimately coupled to layer degrees of freedom and Berry curvature. The layer-dependent electrostatic potential associated with different FE configurations controls the layer character of the band-edge states, thereby locking the Berry curvature to specific layer channels. As a result, bilayer ReIrGe2Se6 enables switching between an anomalous valley Hall effect and a layer-locked anomalous valley Hall effect, providing nonvolatile control of layer, valley, and spin-resolved transport responses. In addition, magnetization reversal switches the valley and spin channels while preserving the layer-resolved character. These results establish bilayer ReIrGe2Se6 as a multistate ferroelectric platform for programmable Berry-curvature related transport, offering microscopic insight into topology based multifunctional electronic and valleytronic devices.
The authors have withdrawn this manuscript because the current analysis is incomplete and the conclusions require substantial revision. The authors do not plan to resubmit a revised version at this time