1. Department of Electrical and Computer Engineering, University of Illinois Chicago, Chicago, Illinois 60607, United States
2. Department of Electrical and Computer Engineering, Rice University, Houston, Texas 70005, United States
3. Applied Physics Graduate Program, Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States
4. Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States
5. Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
6. Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
7. Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
8. Maryland NanoCenter, University of Maryland, College Park, Maryland 20742, United States
9. The Hakubi Center for Advanced Research, Kyoto University, Kyoto 606-8501, Japan
10. Department of Physics I, Kyoto University, Kyoto 606-8502, Japan