journal article·2021-03-23Open access

Band-Order Anomaly at the γ-Al2O3/SrTiO3 Interface Drives the Electron-Mobility Boost

Alla Chikina, Dennis V. Christensen, Vladislav Borisov, Marius-Adrian Husanu, Yunzhong Chen, Xiaoqiang Wang, Thorsten Schmitt, Milan Radovic, Naoto Nagaosa, Andrey S. Mishchenko, Roser Valentí, Nini Pryds, Vladimir N. Strocov

ACS Nano· Volume 15· Issue 3

Abstract

The rich functionalities of transition-metal oxides and their interfaces bear an enormous technological potential. Its realization in practical devices requires, however, a significant improvement of yet relatively low electron mobility in oxide materials. Recently, a mobility boost of about 2 orders of magnitude has been demonstrated at the spinel-perovskite γ-Al2O3/SrTiO3 interface compared to the paradigm perovskite-perovskite LaAlO3/SrTiO3 interface. We explore the fundamental physics behind this phenomenon from direct measurements of the momentum-resolved electronic structure of this interface using resonant soft-X-ray angle-resolved photoemission. We find an anomaly in orbital ordering of the mobile electrons in γ-Al2O3/SrTiO3 which depopulates electron states in the top SrTiO3 layer. This rearrangement of the mobile electron system pushes the electron density away from the interface, which reduces its overlap with the interfacial defects and weakens the electron-phonon interaction, both effects contributing to the mobility boost. A crystal-field analysis shows that the band order alters owing to the symmetry breaking between the spinel γ-Al2O3 and perovskite SrTiO3. Band-order engineering, exploiting the fundamental symmetry properties, emerges as another route to boost the performance of oxide devices.
Source: europepmc · Quality: candidate unverified · Source record ↗

Research context

OpenAlex topics: Electronic and Structural Properties of Oxides · Magnetic and transport properties of perovskites and related materials · Semiconductor materials and devices

SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.

Affiliations

Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland

Institute of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus, Denmark

Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark

Institut für Theoretische Physik, Goethe-Universität Frankfurt am Main, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany

Department of Physics and Astronomy, Uppsala University, Box 516, 5120 Uppsala, Sweden

National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan

Funding

Schweizerischer Nationalfonds zur F?rderung der Wissenschaftlichen Forschung · Staatssekretariat f?r Bildung, Forschung und Innovation · Deutsche Forschungsgemeinschaft · Core Research for Evolutional Science and Technology · Unitatea Executiva pentru Finantarea Invatamantului Superior, a Cercetarii, Dezvoltarii si Inovarii

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