Ferroelectric switchable magnon valley and nonlinear Hall effect in type-I multiferroics

Electric control of magnetism at room temperature is crucial for developing next-generation high-performance spintronics. However, the intrinsic incompatibility between ferroelectricity and magnetism in crystal symmetry, along with the absence of strong magnetoelectric coupling mechanisms, continues to pose major challenges. In this work, we propose a general theoretical framework for magnon manipulation based on ferroelectric polarization switching in two-dimensional multiferroics. Our results demonstrate that, in monolayer hexagonal multiferroics, ferroelectric switching can significantly modulate the intralayer spin exchanges, enabling nonvolatile ferroelectric control of magnons. More importantly, ferroelectric polarization reversal leads to a sign change in the Berry curvature, ensuring effective control over the valley and nonlinear Hall response of magnons. Combining density functional theory calculations, we further identify a class of material candidates with Curie temperatures near room temperature. Our results provide a new way toward low-power and ferroelectrically controllable spintronics.