  KTaO3 has recently attracted attention as a model system to study the
interplay of quantum paraelectricity, spin-orbit coupling, and
superconductivity. However, the high and low vapor pressures of potassium and
tantalum present processing challenges to creating interfaces clean enough to
reveal the intrinsic quantum properties. Here, we report superconducting
heterostructures based on electronic-grade epitaxial (111) KTaO3 thin films.
Electrical and structural characterizations reveal that two-dimensional
electron gas at the heterointerface between amorphous LaAlO3 and KTaO3 thin
film exhibits significantly higher electron mobility, superconducting
transition temperature and critical current density than those in bulk single
crystal KTaO3-based heterostructures owing to cleaner interface in KTaO3 thin
films. Our hybrid approach may enable epitaxial growth of other alkali
metal-based oxides that lie beyond the capabilities of conventional methods.
