1. Peter
Grünberg Institut (PGI-7) and JARA−Fundamentals of Future
Information Technologies, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
2. Institute
of Inorganic Chemistry and JARA−Fundamentals of Future Information
Technologies, RWTH Aachen University, D-52074 Aachen, Germany