Emerging Multifunctionality in 2D Ferroelectrics: A Theoretical Review of the Interplay With Magnetics, Valleytronics, Mechanics, and Optics

2D ferroelectric materials present promising applications in information storage, sensor technology, and optoelectronics through their coupling with magnetics/valleytronics, mechanics, and optics, respectively. The integration of 2D ferroelectrics with magnetism enhances data storage density in memory devices by enabling electric‐field‐controlled magnetic states. Ferroelectric‐valley coupling holds promise for high‐speed, low‐energy electronics by leveraging the electrical control of valley polarization. Ferroelectric‐strain coupling results in various polar topologies, with potential applications in high‐density data storage technologies and sensor devices. Moreover, the coupling between ferroelectrics and optics facilitates the development of nonlinear photonics based on ferroelectric materials. This review summarizes the latest theoretical progress in the coupling mechanisms, including the Dzyaloshinskii‐Moriya‐interaction‐induced magnetoelectric coupling, symmetry‐linked ferroelectric‐valley coupling, ferroelectric‐strain‐coupling‐generated polar topologies, and second‐harmonic generation through ferroelectric‐light interactions. The current challenges and future opportunities in harnessing the coupling in 2D ferroelectric materials for multifunctional applications are provided. This article reviews the latest research advancements in the critical interplay between 2D ferroelectricity and magnetic, valleytronic, mechanical, and optical phenomena. It elucidates the role of fundamental degrees of freedom‐charge, spin, valley, lattice, and excitation‐in driving these interactions, and offers an in‐depth analysis of theoretical insights, highlighting the unique properties of 2D ferroelectric materials.