Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 77: Electronic Structure and Spin-Orbit Interaction III
O 77.2: Vortrag
Donnerstag, 14. März 2013, 16:15–16:30, H33
Valence reconstruction at the surface of LaCoO3 thin films studied by resonant x-ray reflectometry — •Jorge E. Hamann-Borrero1,2, Abdullah Radi2, Woo Seok Choi3, Sebastian Macke4, Ronny Sutarto5, Feizhou He5, George A. Sawatzky2, Ho Nyung Lee3, and Vladimir Hinkov4 — 1IFW-Dresden — 2University of British Columbia, Vancouver, Canada — 3Oak Ridge National Laboratory, Materials Science and Technology Division, USA. — 4Max Planck-UBC Centre for Quantum Materials, Vancouver, Canada — 5Canadian Light Source, Saskatoon, Canada
The structural and electronic properties of a set of LaCoO3 (LCO) thin films with and without a LaAlO3 capping layer are studied by means of resonant x-ray reflectometry (RXRR) and x-ray absorption spectroscopy. The data analysis was performed using an element and valence specific approach. Our observations show that, whereas the capped film shows homogeneous and undisturbed electronic properties throughout the whole LCO layer, the uncapped sample suffers a valence disproportionation where the film bulk has a Co3+ character and a Co2+ layer is formed at the film surface.
The origin of this reconstruction and its relation to the magnetism is discussed. Our results demonstrate the power of RXRR in studying fine depth resolved electronic properties in thin films.
The work at Oak Rigde National Laboratory was supported by the U.S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division.