Phase‐Field Simulations in Ferroic Nanodomains: Defect‐Field Driven Microstructure–Functionality Manipulation

The quest for precise defect-field-driven microstructure-functionality manipulation represents a frontier in the design of next-generation ferroic materials. In ferroelastics, ferroelectrics, and ferromagnetics alike, nanoscale domain configurations-such as strain glass, relaxor, and spin glass states-govern critical functional properties, including colossal caloric effects, giant piezoelectricity, and ultralow hysteresis. However, a fragmented understanding for ferroic nanostructure-functionality relations persist across these material classes, largely because existing theoretical and computational descriptions lack a unified treatment of the local fields generated by defects. Based on phase-field modeling, a particularly powerful route to bridge microstructure and functionality, this review synthesizes cross-disciplinary research to establish a universal physical paradigm: defect-induced local suppression fields act as the common microscopic origin that disrupts long-range domain percolation, pins domain walls, and stabilizes functional nanodomains. We demonstrate a cohesive phase-field framework uniquely capable of such targeted microstructure-functionality manipulation, which integrates conventional energy descriptions with quantitatively derived local defect fields, obtained from atomistic simulations and experimental strain mapping, to predictively simulate and rationally tailor complex domain patterns. This review not only unifies the physics governing nanodomain formation and glassy transitions but also hopes to provide a predictive computational toolkit for high-performance applications in sensing, actuation, energy conversion, and solid-state cooling.