1. Stony Brook University, Electrical and Computer Engineering, Stony Brook, New York 11794, USA
2. Brookhaven National Laboratory, Upton, New York 11973, USA
3. National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
4. Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
5. Georgia Institute of Technology, Atlanta, Georgia 30332, USA
6. U.S. Army Research Laboratory, 2800 Powder Mill Rd., Adelphi, Maryland 20783, USA