1. Department of Physics, Indiana University, Bloomington, Indiana 47405, United States
2. Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln, Nebraska 68588, United States
3. Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, United States
4. Electron Microscope Center, Indiana University, Bloomington, Indiana 47405, United States
5. Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
6. Center for Nanophysics & Advanced Materials, University of Maryland, College Park, Maryland 20742, United States
7. Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
8. Quantum Science and Engineering Center, Indiana University, Bloomington, Indiana 47405, United States