1. Department of Materials Science and EngineeringMaterials Research LaboratoryUniversity of Illinois at Urbana‐ChampaignUrbanaIllinois61801USA
2. Materials Research DepartmentToyota Research Institute of North AmericaAnn ArborMichigan48105USA
3. Department of PhysicsStockholm UniversitySE‐106 91StockholmSweden
4. School of Information TechnologyHalmstad UniversityP.O. Box 823SE‐301 18HalmstadSweden