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

Wei Niu, Yu Zhang, Yulin Gan, Dennis Valbjørn Christensen, Merlin von Soosten, Eduardo José Garcia Suárez, Anders Riisager, Xuefeng Wang, Yongbing Xu, Rong Zhang, Nini Pryds, Yunzhong Chen

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Abstract

Two-dimensional electron gases (2DEGs) formed at the interface between two oxide insulators provide a rich platform for the next generation of electronic devices. However, their high carrier density makes it rather challenging to control the interface properties under a low electric field through a dielectric solid insulator, i.e. in the configuration of conventional field-effect transistors. To surpass this long-standing limit, we used ionic liquids as the dielectric layer for electrostatic gating of oxide interfaces in an electric double layer transistor (EDLT) configuration. Herein, we reported giant tunability of the physical properties of 2DEGs at the spinel/perovskite interface of γ-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 3.0×1013 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.
Original languageEnglish
JournalNano Letters
Volume17
Issue number11
Pages (from-to)6878–6885
ISSN1530-6984
DOIs
Publication statusPublished - 2017

Keywords

  • Two2dimensional electron gas
  • Oxide interfaces
  • Ionic liquid
  • Spin-orbital coupling
  • Lifshitz transition

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