Freestanding Perovskite Oxide Membranes: A New Playground for Novel Ferroic Properties and Applications

Abstract Transition metal perovskite oxide membranes and their unique properties have attracted great attention recently and have been developed into one of the research frontiers in condensed matter physics and materials science. Free of constraint imposed by the underlying substrate, freestanding membranes exhibit extraordinary structural tunability and flexibility far exceeding the bulk materials and epitaxial films clamped on substrates, which substantially extends the explorable regime in the phase diagrams. Moreover, high‐quality oxide membranes, even down to a single unit cell, can be synthesized and stacked/integrated with any materials for novel artificial heterostructures and electronic applications. The exceptional structural tunability and stacking ability in oxide membranes provide new knobs to explore the spontaneous symmetry breaking in oxides, providing a fertile playground for emergent primary ferroic/multiferroic properties and electronic applications. Here, the recent progress is briefly reviewed and the promising outlook for future research in ferroic perovskite oxide membranes and their applications is discussed.