1. Werkstoffe der Elektrotechnik & CENIDE, University of Duisburg-Essen, 47057 Duisburg, Germany
2. Institute of Inorganic Chemistry & CENIDE, University of Duisburg-Essen, 45141 Essen, Germany
3. Materials Discovery and Interfaces, Ruhr University Bochum, 44801 Bochum, Germany
4. Faculty of Physics & CENIDE, University of Duisburg-Essen, 47057 Duisburg, Germany