1. CeNSCMR, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Republic of Korea
2. Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
3. Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
4. Department of Materials
Science and Engineering, National Chung Hsing University, Taichung 40227, Taiwan
5. Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
6. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
7. Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan