Band-order anomaly at the γ-Al2O3/SrTiO3 interface drives the electron-mobility boost

  • 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 two orders of magnitude has been demonstrated at the spinel/perovskite {\gamma}-Al2O3/SrTiO3 interface compared to the paradigm perovskite/perovskite LaAlO3/SrTiO3. 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 {\gamma}-Al2O3/SrTiO3 which depopulates electron states in the top STO layer. This rearrangement of the mobile electron system pushes the electron density away from the interface that 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 {\gamma}-Al2O3 and perovskite SrTiO3. The band-order engineering exploiting the fundamental symmetry properties emerges as another route to boost the performance of oxide devices.

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Author:Alla ChikinaORCiDGND, Dennis V. ChristensenORCiD, Vladislav BorisovORCiD, Marius-Adrian HusanuORCiD, Yunzhong ChenORCiD, Xiaoqiang WangORCiDGND, Thorsten SchmittORCiD, Milan RadovicORCiD, Naoto NagaosaORCiD, Andrey S. MishchenkoORCiD, Roser ValentíORCiDGND, Nini PrydsORCiDGND, Vladimir N. StrocovORCiD
URN:urn:nbn:de:hebis:30:3-824669
URL:https://arxiv.org/abs/2104.00498v1
DOI:https://doi.org/10.48550/arXiv.2104.00498
ArXiv Id:http://arxiv.org/abs/2104.00498v1
Parent Title (English):arXiv
Publisher:arXiv
Document Type:Preprint
Language:English
Date of Publication (online):2021/04/01
Date of first Publication:2021/04/01
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2024/02/20
Tag:electron-phonon interactions; electronic band structure; hheterostructures; photoelectron spectroscopy; transition-metal oxides
Issue:2104.00498 Version 1
Edition:Version 1
Page Number:32
HeBIS-PPN:516154974
Institutes:Physik / Physik
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 4.0