1. Joint Research Laboratory Nanomaterials – Technische Universität Darmstadt and Karlsruhe Institute of Technology, Otto-Berndt-Str. 3, 64287 Darmstadt, Germany
2. Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
3. Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany
4. Nano Functional Material Technology Centre (NFMTC), Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, 600036 Chennai, India