1. Peter Grünberg Institute (PGI-9) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
2. Institute
of Semiconductor Electronics, RWTH Aachen University, 52074 Aachen, Germany
3. Institute
of Solid State Physics, Russian Academy of Sciences, Chernogolovka, 142432 Moscow district, Russia
4. Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
5. Peter Grünberg Institute (PGI-8) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany