Fig. 1: Preparation of flexible SRO membranes with different crystal orientations.

a Schematic illustrating the heterostructure growth, lift-off and transfer process for SRO membranes with different orientations. During the preparation, the water-soluble Sr3Al2O6 is used as sacrificial layers. b Flexible SRO membranes (gray area) transferred on soft PDMS. c An AFM image of the freestanding SRO membrane with a sub-nanometer roughness (RMS). Scale bar is 1 μm. d Low-magnification and e atomically resolved plane-viewed HR-TEM image of [111]-oriented freestanding SRO membrane transferred on a TEM grid with holey carbon film. Scale bars are 5 μm and 5 nm in (d) and (e), respectively. The inset in (e) shows the SAED pattern.