1. Institute of Solid State Electronics, Technische Universität Wien, Vienna 1040, Austria
2. Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
3. Physics Institute, Goethe Universität Frankfurt, Frankfurt am Main 60438, Germany
4. Institute of Inorganic and Analytical Chemistry, Goethe Universität Frankfurt, Frankfurt am Main 60438, Germany
5. Institut Néel, CNRS UPR2940, Grenoble 38042, France