1. Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, Sem Sælandsvei 26, 0371 Oslo, Norway
2. SINTEF Materials Physics, Forskningsveien 1, 0373 Oslo, Norway
3. Faculty of Science and Technology, Norwegian University of Life Sciences, 1433 Ås, Norway
4. Department of Mechanical and Aerospace Engineering, Ohio State University, Columbus, Ohio 43210, USA
5. Department of Physics, Ohio State University, Columbus, Ohio 43210, USA