1. Department of Engineering, University of Cambridge, CambridgeCB3 0FA, United Kingdom
2. 2nd Institute of Physics A and JARA-FIT, RWTH Aachen University, 52074Aachen, Germany
3. Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki305-0044, Japan
4. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki305-0044, Japan
5. Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425Jülich, Germany