1. Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, United States
2. Department of Physics, Washington University in St. Louis, St. Louis, Missouri 63130, United States
3. School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
4. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
5. Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee , United States
6. Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States
7. Center for Integrated Nanostructure Physics, Sungkyunkwan University, Gyeonggi-do 16419, Korea
8. Francis Bitter Magnet Laboratory and Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
9. Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
10. National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
11. Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
12. Institute for Materials Science and Engineering, Washington University in St. Louis, St. Louis, Missouri, 63130, United States
13. Department of Physics, Cornell University, Ithaca, New York 14853, United States