1. Peter Grünberg Institute, Electronic Properties (PGI-6); Forschungszentrum Jülich 52425 Jülich Germany
2. Jülich Aachen Research Alliance, Fundamentals of Future Information Technology (JARA-FIT); Forschungszentrum Jülich 52425 Jülich Germany
3. National Institute of Materials Physics; Măgurele 077125 Bucharest Romania
4. Institute of Inorganic Chemistry, RWTH Aachen University; Aachen 52074 Aachen Germany