Nanometer-Thick Sr₂IrO₄ Freestanding Films for Flexible Electronics

We report the structural and optical properties of nanoscale Sr2IrO4 freestanding thin films fabricated using a water-soluble Sr3Al2O6 layer. The coherent lattice structure, phonon modes, two-magnon Raman scattering, and optical absorption spectra of the Sr2IrO4 nanomembrane are analogous to those of the layered iridate epitaxial thin films and single crystals. Remarkably, the formation of 3-unit-cell-thick SrIrO3 and interfacial composite layers alleviates the antiphase boundaries at the Sr2IrO4/Sr3Al2O6 interface, resulting in structurally robust nanomembranes. Our experimental results show that this freestanding thin-film approach of layered oxides can provide techniques for tuning or realizing unprecedented states beyond conventional thin-film methods, suggesting a pathway in achieving flexible layered-oxide electronics.