1. 2nd Institute of Physics B and JARA-FIT, RWTH Aachen University, Otto-Blumenthal-Straße, 52074 Aachen, Germany
2. National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom
3. Peter Grünberg Institute 6 & 9, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
4. Leibniz Institute for Solid State and Materials Research Dresden (IFW), 01171 Dresden, Germany
5. Advanced Microelectronic Center Aachen (AMICA), AMO GmbH, Otto-Blumenthal-Str. 25, 52074 Aachen, Germany
6. Chair of Electronic Devices, RWTH Aachen University, 52074 Aachen, Germany
7. University of Wuppertal, 42285 Wuppertal, Germany