Functional Requirements of Multiferroic and Magnetoelectric Coupled Materials: Structural, Electronic, and ApplicationDriven Perspectives

Abstract

Multiferroic and magnetoelectrically (ME) coupled materials have attracted considerable attention because they simultaneously support at least two ferroic orders and, in the ME subclass, allow one order to be controlled by a conjugate field of the other. Translating these coupled phenomena into viable device technologies imposes a precise and demanding set of material requirements that extend well beyond the simple coexistence of ferromagnetism and ferroelectricity. This review articulates those requirements in a systematic manner, addressing crystal-structural prerequisites, electronic-structure constraints, thermal and chemical stability benchmarks, and the interface engineering criteria relevant to composite ME heterostructures. Bulk single-phase systems, composite laminates, nanostructured films, and emerging two-dimensional (2D) van der Waals multiferroics are each examined through the lens of what the material must deliver, rather than merely what has been observed. Special attention is given to the figures of merit that govern sensor, energyharvesting, memory, and neuromorphic device applications, because the requirements hierarchy shifts substantially depending on the end use. Ongoing challenges in reconciling contradictory structural demands, suppressing leakage currents, and characterizing ME coupling quantitatively are discussed, and pathways toward materials that meet multiple simultaneous requirements are proposed. The article draws on a broad literature base spanning theoretical prediction, synthesis, and functional characterization of representative systems including BiFeO₃- based perovskites, BaTiO₃/CoFe₂O₄ composites, layered Cr₂Ge₂Te₆ and CuCrP₂S₆, and strain-engineered thin films.