1. Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, USA
2. Department of Physics, Arizona State University, Tempe, Arizona 85287, USA
3. Universität Leipzig, Felix-Bloch-Institut für Festkörperphysik, 04103 Leipzig, Germany
4. U.S. Naval Research Laboratory, Washington, DC 20375, USA
5. Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611, USA