1. Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
2. Integrated Graduate School of Medicine, Engineering, and Agricultural Science, University of Yamanashi, Kofu 400-8510 Japan
3. Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada, Baja California 22800, Mexico