1. Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
2. Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
3. Department of Condensed Matter Physics, Masaryk University, Brno, Czech Republic
4. Central European Institute of Technology, Masaryk University, Brno, Czech Republic
5. Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033, Japan