1. Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland
2. Scientific Center for Optical and Electron Microscopy, ETH Zurich, 8093 Zurich, Switzerland
3. Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
4. Arnold Magnetic Technologies, 5242 Birr-Lupfig, Switzerland
5. Department of Physics, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, USA