Chemical stability of the magnetic oxide EuO directly on silicon observed by hard x-ray photoemission spectroscopy

C. Caspers,1,2 M. Muller,1,2,* A. X. Gray,3,4 A. M. Kaiser,1,3,4 A. Gloskovskii,5 C. S. Fadley,3,4 W. Drube,6 and C. M. Schneider1,2,7 1Peter Grunberg Institut (PGI-6), Forschungszentrum Julich, DE-52425 Julich, Germany 2JARA Julich-Aachen Research Alliance, Forschungszentrum Julich, DE-52425 Julich, Germany 3Department of Physics, University of California, Davis, California, USA 4Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA 5Institut fur Analytische und Anorganische Chemie, Johannes Gutenberg-Universitat, DE-55128 Mainz, Germany 6DESY Photon Science, Deutsches Elektronen-Synchrotron, DE-22603 Hamburg, Germany 7Fakultat fur Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), DE-47048 Duisburg, Germany (Received 28 June 2011; revised manuscript received 6 October 2011; published 18 November 2011)