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.
@article{arxiv.1602.06029,
title = {Tunable electron-electron interactions in LaAlO3/SrTiO3 nanostructures},
author = {Guanglei Cheng and Michelle Tomczyk and Alexandre B. Tacla and Hyungwoo Lee and Shicheng Lu and Josh P. Veazey and Mengchen Huang and Patrick Irvin and Sangwoo Ryu and Chang-Beom Eom and Andrew Daley and David Pekker and Jeremy Levy},
journal= {arXiv preprint arXiv:1602.06029},
year = {2016}
}