1. Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany
2. Faculty of Physics, University of Duisburg-Essen and CENIDE, 47053 Duisburg, Germany
3. RWTH Aachen University, 52056 Aachen, Germany
4. Science Institute and Faculty of Physical Sciences, University of Iceland, VR-III, 107 Reykjavík, Iceland
5. Department of Physics, Arab American University, 240 Jenin, Palestine