1. Department of Physics, Faculty of Science and EngineeringÅbo Akademi University Porthansgatan 3 20500 Turku Finland
2. Department of Physics, Chemistry and BiologyLinköping University 581 83 Linköping Sweden
3. Department of Materials Science and EngineeringStanford University Stanford CA 94305 USA
4. Department of PhysicsChalmers University of Technology 412 96 Göteborg Sweden