Emergent Magnetism at the AlO_x/KTaO₃ Interface Probed with mK Transport Measurements

Here we report signatures of emergent magnetism measured through electrical transport on the two-dimensional electron gas (2DEG) hosted at the interface between AlO_x and KTaO₃ (KTO). In samples fabricated to suppress superconductivity we see a gate voltage tuned magnetism characterized by a zero-field transverse voltage that is strongly asymmetric with respect to an applied perpendicular magnetic field and becomes strongly hysteretic at the lowest measured temperatures. These results are discussed for three different crystal terminations of KTO, and interpreted based on the complex spin texture of the KTO surface. Density functional theory results confirm that oxygen vacancies result in a net spin polarization leading to a finite Berry curvature, explaining the transverse voltage and the striking hysteretic behavior. We also discuss compelling related results measured at higher temperatures in non-local differential resistance.

[1] Krantz et al. arxiv.org/abs/2209.10534 (2022)

[2] Krantz and Chandrasekhar, In Preparation. (2022)