Volume 123, Number 4, August 2018
|Number of page(s)||7|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||17 September 2018|
Nature of the charge carriers in LaAlO3-SrTiO3 oxide heterostructures probed using hard X-ray photoelectron spectroscopy
1 Solid State and Structural Chemistry Unit, Indian Institute of Science - Bengaluru 560012, India
2 Deutsches Elektronen-Synchrotron DESY - Notkestrasse 85, D-22607 Hamburg, Germany
3 Université Grenoble Alpes - F-38000 Grenoble, France
4 CEA, LITEN - 17 rue des Martyrs, F-38054 Grenoble, France
5 Department of Physics, University of Tokyo - Tokyo 113-0033, Japan
6 Max-Plank-Institute for Solid State Research - Stuttgart D-70569, Germany
7 RIKEN Center for Emergent Matter Science (CEMS) - Saitama 351-0198, Japan
8 Centre de Physique Theorique, Ecole Polytechnique, CNRS UMR 7644 - F-91128 Palaiseau, France
Received: 24 August 2018
Accepted: 28 August 2018
A proper investigation of the valence band electronic structure is the essential first step towards understanding the intriguing co-existence of several exotic electronic phases like ferromagnetism and superconductivity, in LaAlO3-SrTiO3 heterostructures. In order to comprehend the electronic structure across the LaAlO3-SrTiO3 oxide interface, a detailed valence band investigation has been carried out using variable energy hard X-ray photoelectron spectroscopy and signatures of both low-energy coherent and high-energy features have been observed in the valence band spectra. Our combined experimental and theoretical study suggests that the charge carriers at the interface are weakly correlated and the high-energy feature does not arise from the lower Hubbard band. Instead, this high-energy feature is attributed to in-gap states induced by oxygen vacancies and possible polaron formation.
PACS: 73.20.-r – Electron states at surfaces and interfaces / 79.60.Jv – Interfaces; heterostructures; nanostructures / 79.60.-i – Photoemission and photoelectron spectra
© EPLA, 2018
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