Diluted Oxide Interfaces with Tunable Ground States

TL;DR

This study demonstrates that alloying LaAlO3 with LaMnO3 at the oxide interface allows for tunable electronic and magnetic ground states, including superconductivity and ferromagnetism, without lattice disorder or polarity change.

Contribution

We reveal a novel method to control the ground state of oxide interfaces by Mn-doping, enabling tailored electronic and magnetic properties for device applications.

Findings

Lifshitz transition at x=0.225 with peak superconducting temperature of 255 mK

Emergence of ferromagnetism at x >= 0.25

Simultaneous superconductivity and anomalous Hall effect at x=0.3

Abstract

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, we report an unforeseen tunability of the phase diagram of LAO/STO 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, the interface undergoes a Lifshitz transition at x = 0.225 across a critical carrier density of nc= 2.8E13 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, we achieve reproducibly a same device with both signatures of superconductivity and clear anomalous Hall effect. This provides a unique and effective way to tailor oxide interfaces for designing on-demand electronic and spintronic devices.