1. Research Group Christiansen; Helmholtz-Zentrum Berlin; Hahn-Meitner-Platz 1 14109 Berlin Germany
2. Max Planck Institute for the Science of Light; Staudtstr. 2 91058 Erlangen Germany
3. Functional Oxides for Energy-Efficient Information Technology; Helmholtz-Zentrum Berlin; Hahn-Meitner-Platz 1 14109 Berlin Germany
4. Solid State Electronics Department; University of Duisburg-Essen; Lotharstr. 55 47048 Duisburg Germany
5. Faculty of Engineering; University of New South Wales; Sydney NSW 2052 Australia
6. Department for Materials Science; Friedrich-Alexander-University; Cauerstr. 6 91058 Erlangen Germany
7. Department of Physics; Freie Universität Berlin; Kaiserswerther Str. 16-18 14195 Berlin Germany