1. Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
2. Laboratory of Physics, Faculty of Natural Sciences, Tampere University of Technology, FI-33101 Tampere, Finland.
3. Peter Grünberg Institut PGI-1 and Jülich Aachen Research Alliance-HPC, Forschungszentrum Jülich, D-52425 Jülich, Germany.