Emergent Freestanding Complex Oxide Membranes for Multifunctional Applications.

Correlated complex oxides feature tightly coupled charge, spin, orbital, and lattice degrees of freedom, which give rise to rich correlated behavior. Freestanding oxide membranes render these materials into tunable quasi-2D platforms that enable multifunctional and reconfigurable devices. This Review surveys recent advances in the research of freestanding oxide membranes, highlighting their coupled correlated properties. We focus on three development pathways: (i) strain-free membranes, (ii) strained membranes, and (iii) van der Waals-integrated heterostructures. This organization begins with the intrinsic properties of oxide membranes, then examines mechanical tuning, heterogeneous integration, and multiphysics coupling to provide a comprehensive account of the field's development. Finally, we evaluate practical challenges, including high-quality surfaces, robust multiphysics coupling, wafer-scale transfer, and silicon-compatible heterogeneous integration. Addressing these challenges will enable scalable, high-yield manufacturing and expand the design space for oxide-based architectures, thereby accelerating the transition from laboratory demonstrations to industry-ready systems.