1. Peter Grünberg Institut PGI-1 and JARA/HPC, Forschungszentrum Jülich, D-52425 Jülich, Germany
2. Laboratory of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland
3. Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
4. COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland