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Materials with a large linear magnetoresistance (MR) are great candidates for magnetic sensors, but rarity boosts investigations for exploring this MR in material physics. 2D electron system (2DES) formed at the nonisostructural heterointerfaces between γ‐Al2O3 (GAO) and SrTiO3 (STO) provides plenty of intriguing or even superior emergent properties compared with the conventional isomorphic all‐perovskite counterparts. Herein, a large MR exceeding 2000% in magnitude at the magnetic GAO/STO heterointerfaces with a high carrier mobility of 30 000 cm2 V−1 s−1 at low temperature is demonstrated. In contrast to the quadratic dependence on the magnetic field of the conventional oxide 2DES, MR in GAO/STO is linear and nonsaturating at high fields, which is stemmed from the magnetic inhomogeneities‐induced inhomogeneous conductivities. In addition, weak antilocalization effect gives rise to an extra quantum correction to the MR in low‐field region. Furthermore, a general qualitative picture of MR proportional to the mobility is established. These findings reveal the nonisostructural GAO/STO heterointerface is of great promise in magnetic sensor‐based practical memory applications and transistor designs.

Two-dimensional electron gas (2DEG) formed at the heterointerface between two oxide insulators hosts plenty of emergent phenomena and provides new opportunities for electronics and photoelectronics. However, despite being long sought after, on-demand properties controlled through a fully optical illumination remain far from being explored. Herein, a giant tunability of the 2DEG at the interface of γ-Al 2 O 3 /SrTiO 3 through a fully optical gating is discovered. Specifically, photon-generated carriers lead to a delicate tunability of the carrier density and the underlying electronic structure, which is accompanied by the remarkable Lifshitz transition. Moreover, the 2DEG can be optically tuned to possess a maximum Rashba spin−orbit coupling, particularly at the crossing region of the sub-bands with different symmetries. First-principles calculations essentially well explain the optical modulation of γ-Al 2 O 3 /SrTiO 3 . Our fully optical gating opens a new pathway for manipulating emergent properties of the 2DEGs and is promising for on-demand photoelectric devices.

The nontrivial Berry phase in correlated oxide heterostructures has been highly attractive due to the Rashba spin–orbit interactions originating from the inversion symmetry breaking at the heterointerfaces. Despite the theoretically predicated nontrivial π Berry phase in Rashba systems, its experimental detection among all Rashba oxide interfaces remains elusive. Here, we report a nontrivial Berry phase at the interface between γ-Al2O3 and SrTiO3 as evidenced by the quantum oscillations. Analysis of transport properties under the high magnetic field up to 32 T reveals the weak anti-localization (WAL) effect and Shubnikov–de Haas (SdH) oscillations. Both the WAL effect and the nontrivial π Berry phase extracted from the SdH oscillations manifest the significance of the Rashba spin–orbit coupling in γ-Al2O3/SrTiO3. Physical quantities concerning the Fermi surface, such as effective mass, scattering time, etc., are experimentally accessed as well. Our work provides insights into the nontrivial Berry phase in correlated oxide interfaces.

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