Quantum confinement at complex oxide interfaces establishes an intricate hierarchy of the strongly correlated d-orbitals which is widely recognized as a source of emergent physics. The most prominent example is the (001) LaAlO3/SrTiO3(LAO/STO) interface, which features a dome-shaped phase diagram of superconducting critical temperature and spin-orbit coupling (SOC) as a function of electrostatic doping, arising from a selective occupancy of t2g orbitals of different character. Here we study (111)-oriented LAO/STO interfaces - where the three t2g orbitals contribute equally to the sub-band states caused by confinement - and investigate the impact of this unique feature on electronic transport. We show that transport occurs through two sets of electron-like sub-bands, and the carrier density of one of the sets shows a non-monotonic dependence on the sample conductance. Using tight-binding modeling, we demonstrate that this behavior stems from a band inversion driven by on-site Coulomb interactions. The balanced contribution of all t2g orbitals to electronic transport is shown to result in strong SOC with reduced electrostatic modulation.
@article{arxiv.1808.03063,
title = {Band inversion driven by electronic correlations at the (111) LaAlO$_3$/SrTiO$_3$ interface},
author = {A. M. R. V. L. Monteiro and M. Vivek and D. J. Groenendijk and P. Bruneel and I. Leermakers and U. Zeitler and M. Gabay and A. D. Caviglia},
journal= {arXiv preprint arXiv:1808.03063},
year = {2019}
}