High-quality antiferromagnetic Mott insulator thin films of LaTiO₃ (LTO) were epitaxially grown onto SrTiO₃ (STO) (110) substrates using the pulsed laser deposition. The LTO/STO heterostructures are not only highly conducting and ferromagnetic, but also show Kondo effect, Shubnikov-de Haas (SdH) oscillations with a nonzero Berry phase of π, and low-field hysteretic negative magnetoresistance (MR). Angle-dependent SdH oscillations and a calculation of the thickness of the interfacial conducting layer indicate the formation of a 4-nm high mobility two-dimensional electron gas (2DEG) layer at the interface. Moreover, an amazingly large low-field negative MR of ∼61.8% is observed at 1.8 K and 200 Oe, which is approximately one to two orders of magnitude larger than those observed in other spin-polarized 2DEG oxide systems. All these results demonstrate that the 2DEG is spin-polarized and the 4-nm interfacial layer is ferromagnetic, which are attributed to the presence of magnetic Ti³⁺ ions due to interfacial oxygen vacancies and the diffusion of La³⁺ ions into the STO substrate. The localized Ti³⁺ magnetic moments couple to high mobility itinerant electrons under magnetic fields, giving rise to the observed low-field MR. Our work demonstrates the great potential of antiferromagnetic titanate oxide interface for designing spin-polarized 2DEG and spintronic devices.

使用脉冲激光沉积在 SrTiO ₃ (STO) (110) 基板上外延生长LaTiO ₃ (LTO)的高质量反铁磁莫特绝缘体薄膜。 LTO/STO异质结构不仅具有高导电性和铁磁性，而且还表现出近藤效应、具有非零π贝里相的舒布尼科夫-德哈斯（SdH）振荡和低场磁滞负磁阻（MR）。角度相关的 SdH 振荡和界面导电层厚度的计算表明在界面处形成了 4 nm 高迁移率二维电子气 (2DEG) 层。此外，在 1.8 K 和 200 Oe 下观察到令人惊讶的大低场负 MR，约为 61.8%，这比在其他自旋极化 2DEG 氧化物系统中观察到的大约大一到两个数量级。所有这些结果表明，2DEG 是自旋极化的，并且 4 nm 界面层是铁磁性的，这归因于由于界面氧空位而导致磁性 Ti ^{3+离子的存在以及 La 3+}离子扩散到 STO 衬底中。局域 Ti ³⁺磁矩与磁场下的高迁移率流动电子耦合，产生了观察到的低场 MR。我们的工作证明了反铁磁氧化钛界面在设计自旋极化二维电子气和自旋电子器件方面的巨大潜力。