1. Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
2. Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027, United States
3. Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, PO Box 5000, Upton, New York 11973, United States
4. Department of Applied Physics and Applied Mathematics, Columbia University, 500 W 120th St, New York, New York 10027, United States
5. National High Magnetic Field Laboratory, 1800 E Paul Dirac Dr, Tallahassee, Florida 32310, United States
6. Nanoscience Initiative at Advanced Science Research Center, Graduate Center of the City University of New York, 85 St. Nicholas Terrace, New York, New York 10031, United States
7. Department of Physics, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States