Giant tunability of the two-dimensional electron gas at the interface of gamma-Al2O3/SrTiO3

TL;DR

This study demonstrates the giant tunability of the electronic properties of 2DEGs at the gamma-Al2O3/SrTiO3 interface through ionic-liquid gating, revealing a Lifshitz transition, enhanced spin-orbit interaction, and increased electron mobility.

Contribution

It introduces a highly tunable 2DEG system at the gamma-Al2O3/SrTiO3 interface with significant control over electronic phases via ionic-liquid gating.

Findings

Lifshitz transition at critical carrier density of 3E13 cm-2

Enhanced Rashba spin-orbit interaction at the transition

Electron mobility increased by over 6 times with gating

Abstract

Herein, we reported giant tunability of the physical properties of 2DEGs at the spinel/perovskite interface of {\gamma}-Al2O3/SrTiO3 (GAO/STO). By modulating the carrier density thus the band filling with ionic-liquid gating, the system experiences a Lifshitz transition at a critical carrier density of 3E13 cm-2, where a remarkably strong enhancement of Rashba spin-orbit interaction and an emergence of Kondo effect at low temperatures are observed. Moreover, as the carrier concentration depletes with decreasing gating voltage, the electron mobility is enhanced by more than 6 times in magnitude, leading to the observation of clear quantum oscillations. The great tunability of GAO/STO interface by EDLT gating not only shows promise for design of oxide devices with on-demand properties, but also sheds new light on the electronic structure of 2DEG at the non-isostructural spinel/perovskite interface.