Gate-tunable band structure of the LaAlO$_3$-SrTiO$_3$ interface

TL;DR

This study demonstrates that the electronic band structure at the LaAlO$_3$-SrTiO$_3$ interface can be tuned by gate voltage, revealing a Lifshitz transition and the importance of electronic correlations in modeling the system.

Contribution

It combines magnetotransport experiments with self-consistent calculations to show gate-tunable band structure and Lifshitz transition at the oxide interface, highlighting the role of electronic correlations.

Findings

Observation of a Lifshitz transition at a specific carrier density.

Carrier density in one band decreases with increasing gate voltage.

Electronic correlations are essential for accurate modeling.

Abstract

The 2-dimensional electron system at the interface between LaAlO$_{3}$ and SrTiO$_{3}$ has several unique properties that can be tuned by an externally applied gate voltage. In this work, we show that this gate-tunability extends to the effective band structure of the system. We combine a magnetotransport study on top-gated Hall bars with self-consistent Schr\"odinger-Poisson calculations and observe a Lifshitz transition at a density of $2.9\times10^{13}$ cm$^{-2}$. Above the transition, the carrier density of one of the conducting bands decreases with increasing gate voltage. This surprising decrease is accurately reproduced in the calculations if electronic correlations are included. These results provide a clear, intuitive picture of the physics governing the electronic structure at complex oxide interfaces.