Investigation of epitaxial LaNiO3-x thin films by High-Energy XPS
|Sigitas Mickevicius 2, Sergej Grebinskij 2, Vladimir Bondarenka 2, Vengalis V. Bonifacas 2, Kristina Sliuziene 2, Bronislaw A. Orlowski 3, Wolfgang Drube 1|
1. Hamburger Synchrotronstrahlungslabor HASYLAB (HASYLAB), Notkestrasse 85, Hamburg D-22603, Germany
In recent years certain perovskite-related metallic oxides, such as high-Tc superconductors, the compounds exhibiting giant magnetoresistance and conductive oxides, are intensively studied. The current interest in thin films of high temperature superconductors has made the problem of a suitable substrate an important point for epitaxy to be successfully. A number of Ln-containing (Ln = La, Pr and Nd) oxide crystals have been employed as the substrate material and many are under investigation now. There have been numerous studies on their morphology, structural, thermodynamic, magnetic, elastic properties and crystal growth.
The epitaxial LaNiO3-x films prepared on monocrystalline NdGaO3 demonstrate the excellent in-plane orientation. It is known, that the significant segregation of elements takes place for chemically synthesized LaNiO3-x samples. X-ray photoelectron spectroscopy (XPS) as the surface analysis method provides the direct information on the species concentration and their valence states. In this work we performed High-Energy XPS spectroscopy studies of the surface and volume composition of LaNiO3-x deposited on NdGaO3 substrate by a reactive d.c. magnetron sputtering.
The photoemission data were obtained with the Tunable High-Energy X-ray Photoelectron Spectrometer at the X-ray wiggler beam line BW2 of synchrotron storage ring at HASYLAB. The angle dependent data were obtained by rotating the sample relative to the incoming beam and to the electron analyzer. Comparison of the spectra recorded at normal emission and grazing emission angle allows distinguishing surface and volume atoms contribution to the measured spectra.
The main core level photoemission spectra of La, Ni, O as well as valence band spectra were measured at different emission angles. The obtained results have been analysed in terms of surface-volume ratio: composition, valence states and the concentration of hydroxyl groups in the epitaxial LaNiO3-x films
Presentation: poster at E-MRS Fall Meeting 2005, Symposium B, by Sigitas Mickevicius
See On-line Journal of E-MRS Fall Meeting 2005
Submitted: 2005-05-19 19:06 Revised: 2009-06-07 00:44