1. Department of Physics, University of Washington, Seattle, Washington 98195, United States
2. Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, United States
3. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
4. Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
5. Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States