Oxygen vacancy induced electronic phenomena of KTaO₃

Emergent two-dimensional electron gas (2-DEG) at complex oxide interfaces has been a subject of huge interest over the last fifteen years. The discovery of 2-DEG at the interface between LaAlO₃ and SrTiO₃ has lead to a massive search for other 2-DEG systems. Various mechanisms viz. polar catastrophe, cationic intermixing and oxygen vacancy have been proposed to explain the origin of interfacial conduction. Since more than one mechanism can be operative simultaneously, well-defined understanding remains a challenge. In this work, we report on sole effect of oxygen vacancy on electronic structure modification of a prototypical perovskite KTaO₃ by deliberately creating oxygen vacancies in a pristine single-crystalline sample. Oxygen deficiency turns KTaO₃ into a metal which shows many interesting quantum transport phenomena such as Shubnikov-de Haas oscillations, anomalous Hall effect. Ab-initio calculations find the existence of vacancy induced local magnetic moments on Ta around vacancy and the skew scattering of conduction electrons by these local moments lead to the observation of anomalous Hall effect.