1. Peter
Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
2. Elettra-Sincrotrone, S.C.p.A, S.S 14-km 163.5
in AREA Science Park, Basovizza, 34149 Trieste, Italy
3. Department
of Materials Science and Engineering and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, United States
4. Institute
for Electronic Materials, IWE2, RWTH Aachen University, 52074 Aachen, Germany