TY  - JOUR
A1  - Chikina, Alla
A1  - Christensen, Dennis V.
A1  - Borisov, Vladislav
A1  - Husanu, Marius-Adrian
A1  - Chen, Yunzhong
A1  - Wang, Xiaoqiang
A1  - Schmitt, Thorsten
A1  - Radovic, Milan
A1  - Nagaosa, Naoto
A1  - Mishchenko, Andrey S.
A1  - Valentí, Roser
A1  - Pryds, Nini
A1  - Strocov, Vladimir N.
T1  - Band-order anomaly at the γ-Al2O3/SrTiO3 interface drives the electron-mobility boost
T2  - ACS Nano
N2  - 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.
KW  - transition-metal oxides
KW  - heterostructures
KW  - photoelectron spectroscopy
KW  - electronic band structure
KW  - electron−phonon interactions
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/82468
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-824681
SN  - 1936-086X
VL  - 15
IS  - 3
SP  - 4347
EP  - 4356
PB  - American Chemical Society
CY  - Washington, DC
ER  -