Freestanding Sr₂IrO₄ nanomembranes: structural and optical properties

We report the structural and optical properties of nanoscale freestanding Sr₂IrO₄ thin film fabricated using a sacrificial water-soluble Sr₃Al₂O₆ layer. The coherent lattice structure, phonon modes, two-magnon Raman scattering, and optical absorption spectra of the freestanding Sr₂IrO₄ nanomembrane are analogous to those of the layered iridate epitaxial thin-films and single crystals. Remarkably, the 3-unit-cell-thick SrIrO₃ interfacial layers alleviate the formation of antiphase boundaries at the Sr₂IrO₄/Sr₃Al₂O₆ interface, resulting in structurally-robust freestanding thin-film. 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 two-dimensional layered oxides electronics.