1. Peter-Grünberg-Institut 6, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
2. Center
for Nanoscale Science and Technology, NIST, Gaithersburg, Maryland 20899, United States
3. Maryland
NanoCenter, University of Maryland, College Park, Maryland 20742, United States
4. Faculty
of Mathematics and Physics, Charles University, 180 00 Prague, Czech Republic
5. Oak Ridge National Laboratory, Oak
Ridge, Tennessee 37831, United States