1. Solid Surface Analysis, Institute of Physics, Chemnitz University of Technology, 09126 Chemnitz, Germany
2. Semiconductor Physics, Institute of Physics, Chemnitz University of Technology, 09126 Chemnitz, Germany
3. Functional Magnetic Materials, Institute of Physics, Chemnitz University of Technology, 09126 Chemnitz, Germany
4. Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
5. Department of Applied Physics, Hebrew University of Jerusalem, 91904 Jerusalem, Israel
6. Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, 91904 Jerusalem, Israel
7. Institute of Physics, Polish Academy of Sciences, 02-668 Warszawa, Poland