Atomic Origin of Interface-Dependent Oxygen Migration by Electrochemical Gating at the LaAlO3-SrTiO3 Heterointerface

Dongsheng Song; Deqing Xue; Shengwei Zeng; Changjian Li; Thirumalai Venkatesan; Ariando Ariando; Stephen J Pennycook

doi:10.1002/advs.202000729

Atomic Origin of Interface-Dependent Oxygen Migration by Electrochemical Gating at the LaAlO₃-SrTiO₃ Heterointerface

Adv Sci (Weinh). 2020 Jun 28;7(15):2000729. doi: 10.1002/advs.202000729. eCollection 2020 Aug.

Authors

Dongsheng Song^{1

2}, Deqing Xue¹, Shengwei Zeng^{2

3}, Changjian Li^{1

2}, Thirumalai Venkatesan^{1

2

3}, Ariando Ariando^{2

3}, Stephen J Pennycook^{1

2}

Affiliations

¹ Department of Materials Science and Engineering National University of Singapore Singapore 117575 Singapore.
² NUSNNI-Nanocore National University of Singapore Singapore 117411 Singapore.
³ Department of Physics National University of Singapore Singapore 117542 Singapore.

Abstract

Electrical control of material properties based on ionic liquids (IL) has seen great development and emerging applications in the field of functional oxides, mainly understood by the electrostatic and electrochemical gating mechanisms. Compared to the fast, flexible, and reproducible electrostatic gating, electrochemical gating is less controllable owing to the complex behaviors of ion migration. Here, the interface-dependent oxygen migration by electrochemical gating is resolved at the atomic scale in the LaAlO₃-SrTiO₃ system through ex situ IL gating experiments and on-site atomic-resolution characterization. The difference between interface structures leads to the controllable electrochemical oxygen migration by filling oxygen vacancies. The findings not only provide an atomic-scale insight into the origin of interface-dependent electrochemical gating but also demonstrate an effective way of engineering interface structure to control the electrochemical gating.

Keywords: LaAlO3/SrTiO3; electrochemical gating; ionic liquid gating; oxygen migration.