1. Center for High Technology Materials, The University of New Mexico 1 , Albuquerque, New Mexico 87108, USA
2. Center for Integrated Nanotechnologies, Sandia National Laboratories 2 , Albuquerque, New Mexico 87108, USA
3. Department of Physics, Arizona State University 3 , Tempe, Arizona 85287, USA
4. U.S. Naval Research Laboratory 4 , Washington, DC 20375, USA
5. Electrical and Computer Engineering, The University of New Mexico 5 , Albuquerque, New Mexico 87108, USA