High-Mobility Spin-Polarized Two-Dimensional Electron Gases at EuO/KTaO3 Interfaces

Two-dimensional electron gases (2DEGs) at oxide interfaces, which provide unique playgrounds for emergent phenomena, have attracted increasing attention in recent years. While most of the previous works focused on the 2DEGs at LaAlO3/SrTiO3 interfaces, here we report on a new kind of 2DEGs formed between a magnetic insulator EuO and a high-k perovskite KTaO3. The 2DEGs are not only highly conducting, with a maximal Hall mobility of 111.6 cm2/V s at 2 K, but also well spin polarized, showing strongly hysteretic magnetoresistance up to 25 K and well-defined anomalous Hall effect up to 70 K. Moreover, unambiguous correspondences between the hysteretic behaviors of 2DEGs and the EuO layer are captured, suggesting the proximity effect of the latter on the former. This is confirmed by the results of density-functional theory calculations: Through interlayer exchange, EuO drives the neighboring TaO2 layer into a ferromagnetic state. The present work opens new avenues for the exploration for high performance spin-polarized 2DEGs at oxide interfaces.