1. Department
of Physics, The Ohio State University, Columbus, Ohio 43210, United States
2. School
of Natural Sciences, University of California, Merced, California 95343, United States
3. IBM Research
Division,
Almaden Research Center, San Jose, California 95120, United States
4. School of Materials
Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea, 688-798