1. Institute of Nano- and Biotechnologies (INB); Aachen University of Applied Sciences; Heinrich-Mußmann-Str. 1, 52428 Jülich Germany
2. Peter Grünberg Institute (PGI-8); Forschungszentrum Jülich GmbH; 52525 Jülich Germany
3. Institute for Materials Research (IMO); Hasselt University; Wetenschapspark 1, 3590 Diepenbeek Belgium