Diluted Oxide Interfaces with Tunable Ground States

The metallic interface between two oxide insulators, such as LaAlO3/SrTiO3 (LAO/STO), provides new opportunities for electronics and spintronics. However, due to the presence of multiple orbital populations, tailoring the interfacial properties such as the ground state and metal‐insulator transitions remains challenging.

Here, an unforeseen tunability of the phase diagram of LAO/STO is reported by alloying LAO with a ferromagnetic LaMnO3 insulator without forming lattice disorder and at the same time without changing the polarity of the system. By increasing the Mn‐doping level, x, of LaAl1−xMnxO3/STO (0 ≤ x ≤ 1), the interface undergoes a Lifshitz transition at x = 0.225 across a critical carrier density of nc = 2.8 × 1013 cm−2, where a peak TSC ≈255 mK of superconducting transition temperature is observed.

Moreover, the LaAl1−xMnxO3 turns ferromagnetic at x ≥ 0.25. Remarkably, at x = 0.3, where the metallic interface is populated by only dxy electrons and just before it becomes insulating, a same device with both signatures of superconductivity and clear anomalous Hall effect (7.6 × 1012 cm−2 < ns ≤ 1.1 × 1013 cm−2) is achieved reproducibly.

This provides a unique and effective way to tailor oxide interfaces for designing on‐demand electronic and spintronic devices.