Dual-Gate Modulation of Carrier Density and Disorder in an Oxide Two-Dimensional Electron System

TL;DR

This study demonstrates how a dual-gate setup on LaAlO3/SrTiO3 interfaces allows independent tuning of carrier density and disorder, revealing their distinct effects on quantum phenomena in oxide two-dimensional electron systems.

Contribution

It introduces a hybrid liquid/solid dual-gate device enabling independent control of electron confinement and scattering in oxide interfaces, advancing understanding of their quantum properties.

Findings

Dual-gate control induces nonlinear Hall effect.

Wide tunability of density and disorder achieved.

Poisson-Schrodinger model explains the phenomena.

Abstract

Carrier density and disorder are two crucial parameters that control the properties of correlated two-dimensional electron systems. In order to disentangle their individual contributions to quantum phenomena, independent tuning of these two parameters is required. Here, by utilizing a hybrid liquid/solid electric dual-gate geometry acting on the conducting LaAlO3/SrTiO3 heterointerface, we obtain an additional degree of freedom to strongly modify the electron confinement profile and thus the strength of interfacial scattering, independent from the carrier density. A dual-gate controlled nonlinear Hall effect is a direct manifestation of this profile, which can be quantitatively understood by a Poisson-Schrodinger subband model. In particular, the large nonlinear dielectric response of SrTiO3 enables a very wide range of tunable density and disorder, far beyond that for conventional semiconductors. Our study provides a broad framework for understanding various reported phenomena at the LaAlO3/SrTiO3 interface.