Enhancement of Superconductivity in Electronic-Grade KTaO₃ Heterostructures Grown by Hybrid PLD

The superconductivity emerging from the two-dimensional electron system in LaAlO₃ grown on (111) KTaO₃ bulk single crystals provides a foundation to explore various quantum phenomena, such as quantum paraelectricity and spin-orbit coupling. Epitaxial thin films of KTaO₃ with minimal disorder offer a unique platform to probe intrinsic behavior and study the mechanisms of superconductivity. We have developed superconducting heterostructures based on electronic-grade epitaxial (111) KTaO₃ thin films, synthesized using a novel hybrid approach that combines thermal evaporation of K₂O suboxide with pulsed laser deposition of Ta₂O₅, facilitated by an ultrathin SmScO₃ template. The two-dimensional electron gas at the heterointerface between LaAlO₃ and KTaO₃ thin films demonstrates significantly higher electron mobility, superconducting transition temperature, and critical current density compared to bulk single-crystal KTaO₃-based heterostructures. Cross-sectional STEM analysis reveals a lower density of point defects and a cleaner interface in heteroepitaxial KTaO₃ thin films, in contrast to bulk single-crystal KTaO₃ substrates. We will also discuss additional approaches to enhancing superconductivity in electronic-grade KTaO₃ thin film heterostructures.