1. Peter Grünberg Institute (PGI-7) and JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
2. Faculty 1−Mathematics, Computer Science and Natural Science, RWTH Aachen University, 52062 Aachen, Germany
3. Peter Grünberg Institute (PGI-1) and Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich GmbH and JARA, 52425 Jülich, Germany