Oxide Bicrystals—A Novel Platform for Engineering Quantum Interfaces

Quantum interfaces, essential for next-generation quantum technologies, require precise control over electronic and atomic-scale properties at material junctions. Oxide bicrystals present a novel platform for engineering such interfaces, offering tunable structural and electronic characteristics. In particular, by controlling twist angles, quantum interfaces with enhanced coherence, symmetry-breaking effects, and electronic transport properties can be obtained. In this talk, I will focus on three key aspects of obtaining oxide bicrystals: the synthesis of atomically-precise membranes, the challenges and solutions for producing membranes without or with controlled wrinkles and cracks, and the development of sensitive characterization techniques for bicrystals. Using SrTiO₃ and BaTiO₃ as examples, I will showcase our group's work in achieving thin membranes and their bicrystals (with precise twist angles) with excellent control over thickness, stoichiometry, and surface termination. Additionally, I will introduce the sacrificial layer approach, which yields oxide membranes with a room-temperature dielectric constant of approximately 300. This work offers a materials science perspective on how epitaxy can enhance membrane technology, unlocking new opportunities for applications in energy storage, sensors, and nanoelectronics.