Coexistence of superconductivity and magnetism in AlO_x/KTaO₃ two-dimensional electron gases

We report on measurements of the magnetoresistance of two-dimensional electron gases (2DEGs) that form at the surface of KTaO₃ (KTO) with three different surface crystal orientations: (001), (110) and (111). The 2DEGs are fabricated by depositing a thin layer of AlO_x on the KTO surface. Low temperature magnetic field measurements of the longitudinal and transverse (Hall) resistance show hysteresis in fields both perpendicular to and parallel with the plane of the 2DEGs, a signature of underlying long range magnetic order. This hysteretic behavior persists as the temperature is lowered and the (110) and (111) oriented samples become superconducting, showing a coexistence of superconductivity and magnetism, similar to what has been observed earlier in LAO/STO devices. We report on the behavior of the samples in the superconducting state in both perpendicular and parallel magnetic fields.