1. Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
2. Department of Systems, Control and Information Engineering, National Institute of Technology, Asahikawa College, Asahikawa, Hokkaido 071-8142, Japan
3. Department of Electronics for Informatics, Hokkaido University, Sapporo, Hokkaido 060-0814, Japan
4. Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397, Japan
5. Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
6. Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States