1. Huygens-Kamerlingh
Onnes Laboratory, University of Leiden, 2300 RA Leiden, Netherlands
2. Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
3. Jülich-Aachen
Research Alliance (JARA), Fundamentals of Future Information Technology, 52425, Jülich, Germany
4. Institute of Physics, Polish Academy of Sciences, 02-668, Warsaw, Poland