1. II. Physics Institute, University of Cologne, 50937 Cologne, Germany
2. Institute for Solid State Research, IFW Dresden, 01069 Dresden, Germany
3. Institute of Applied Physics, TU Dresden, 01062 Dresden, Germany
4. Institute for Theoretical Solid State Physics, IFW Dresden, 01069 Dresden, Germany
5. ct.qmat, Dresden-Würzburg Cluster of Excellence-EXC 2147, TU Dresden, 01062 Dresden, Germany
6. Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
7. Faculty of Sciences, Pavol Jozef Safarik University, Park Angelinum 9, 041 54 Kosice, Slovakia
8. Bogolyubov Institute for Theoretical Physics of the National Academy of Sciences of Ukraine, 03143 Kyiv, Ukraine
9. Institute of Solid State and Materials Physics, TU Dresden, 01062 Dresden, Germany