1. SINTEF Materials Physics, P/O Box 124 Blindern,
0314 Oslo, Norway
2. Department of Physics, University of Oslo, P/O
Box 1048 Blindern, 0316 Oslo, Norway
3. Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210, USA;
Department of Physics, Ohio State University, Columbus, Ohio
43210, USA; and Center for Materials Research, Ohio State University, Columbus, Ohio 43210, USA