1. Institute of Physics, Johannes Gutenberg-University, Mainz, Germany
2. Division of Display and Semiconductor Physics, Korea University, Sejong, South Korea
3. Centre for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway
4. Max Planck Institute for Solid State Research, Stuttgart, Germany
5. Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, Jülich, Germany
6. H. H. Wills Physics Laboratory, University of Bristol, Bristol, UK
7. Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich, Germany