Nonvolatile Ferroelectric Manipulation of Topological States in Two-Dimensional Multiferroic van der Waals Heterostructures.

Abstract

Multiferroic materials, including tunable ferrovalley characteristics and band topology, enabled by ferroelectric control at the nanoscale, possess significant potential for technology advances in next-generation magnetoelectric and spintronic applications. However, the realization of this fascinating multifunctionality in nanoscale systems with perpendicular magnetic anisotropy remains unexplored. Here, we propose a class of van der Waals multiferroic heterostructures comprising ferromagnetic, ferrovalley, and ferroelectric layers that exhibit switchable topological states in response to ferroelectric polarization. Taking the In₂Se₃/RuClBr/CrI₃ heterostructure as an example, our first-principles calculations reveal its perpendicular magnetic anisotropy and band topology transition under different ferroelectric polarizations. When the ferroelectric polarization is downward, the heterostructure exhibits a type-III band alignment with metallic properties. Remarkably, when the polarization direction is reversed upward, it demonstrates a type-I band alignment accompanied by the emergence of a quantum anomalous Hall effect. Consequently, by manipulating the ferroelectric polarization direction, the multiferroic heterostructure can switch between normal metal behavior and a nonvolatile topological insulator. This study not only proposes a viable approach for tailoring topological states through multiferroic heterostructures but also demonstrates its potential significance in advancing multifunctional spintronic applications in ferroelectronics, valleytronics, and topology.