1. Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
2. Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
3. Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
4. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
5. Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
6. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States