1. Fourth
Physics Institute and Research Center SCoPE, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
2. Max Planck Institute
for Solid State Research, Heisenbergstrasse
1, 70569 Stuttgart, Germany
3. Department
of Chemistry, University of Cologne, Luxemburger Strasse 116, 50939 Cologne, Germany
4. Department
of Physics, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
5. Department
of Electrical and Systems Engineering, University of Pennsylvania, 200
South 33rd Street, ESE 203 Moore, Philadelphia, Pennsylvania 19104, United States
6. Corporate
Research and Technology, Carl Zeiss AG, Carl-Zeiss-Strasse 22, 73447 Oberkochen, Germany