Step-Edge-Induced Structure Modulation in Freestanding BaTiO₃ Membranes

Freestanding oxide membranes offer a promising pathway for integrating devices on silicon and flexible platforms. Freestanding barium titanate (BaTiO₃, BTO) membranes, in particular, hold significant potential for miniaturized field-effect devices integrated on silicon substrates [1,2]. In this study, we investigate the structural modulations in freestanding BTO membranes caused by strain from one-unit-cell step-edges when these membranes adhere to substrates. Using X-ray nanobeam analysis, we examine the (020) Bragg peak with a spatial resolution of 50 nm across varying temperatures. As anticipated, these structural stripes remain rigid above the Curie temperature (120°C for bulk BTO). Our findings highlight that even subtle step-edges, previously overlooked in the study of freestanding membranes, might significantly impact the physical properties of these membranes. Furthermore, the various orientations of the step edges may introduce an additional degree of freedom, potentially leading to the emergence of new properties.