1. Physics and Astronomy, University of California, Irvine, California 92697, USA
2. INAC/CEA, Grenoble, 17 Avenue des Martyrs, 38054 Grenoble, France
3. Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, Rio de Janeiro 22.290-180, RJ, Brazil
4. Fakultät für Physik and Center for Nanointegration (CeNIDE), Universität Duisburg-Essen, 47048 Duisburg, Germany
5. HGST Research Center, San Jose, California 95135, USA
6. Components Research, Intel, Hillsboro, Oregon 97124, USA