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

摘要

Carrier density and disorder are two crucial parameters that control the properties of correlated two-dimerisional 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 te strongly modify the electron confinement profile and thus the strength of interfacial VrG scattering, independent from the carrier density. A dual-gate controlled nonlinear HalLeffect is a direct manifestation of.this profile, which can be quantitatively understood by a PoissonSchrodinger sub-band 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.