Tunable electron-electron interactions in LaAlO3/SrTiO3 nanostructures

TL;DR

This study demonstrates how LaAlO3/SrTiO3 nanostructures can be electrically tuned to switch electron-electron interactions from attractive to repulsive, enabling potential applications in quantum simulation.

Contribution

The paper reveals a gate-tunable transition in electron-electron interactions in oxide nanostructures, linked to a Lifshitz transition, and highlights their reconfigurability for quantum simulation.

Findings

Observation of a transition from electron pairing to single-electron tunneling.

Identification of a Lifshitz transition associated with interaction sign change.

Demonstration of nanoscale reconfigurability of electron interactions.

Abstract

The interface between the two complex oxides LaAlO3 and SrTiO3 has remarkable properties that can be locally reconfigured between conducting and insulating states using a conductive atomic force microscope. Prior investigations of sketched quantum dot devices revealed a phase in which electrons form pairs, implying a strongly attractive electron-electron interaction. Here, we show that these devices with strong electron-electron interactions can exhibit a gate-tunable transition from a pair-tunneling regime to a single-electron (Andreev bound state) tunneling regime where the interactions become repulsive. The electron-electron interaction sign change is associated with a Lifshitz transition where the dxz and dyz bands start to become occupied. This electronically tunable electron-electron interaction, combined with the nanoscale reconfigurability of this system, provides an interesting starting point towards solid-state quantum simulation.