1. Department of Physics, Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan
2. Graduate School of Information Sciences, Hiroshima City University, Hiroshima 731-3194, Japan
3. Department of Electrical Engineering, Ube National College of Technology, Ube, Yamaguchi 755-8555, Japan
4. Research Center for Condensed Matter Physics, Hiroshima Institute of Technology, Hiroshima 731-5193, Japan
5. Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, Sayo, Hyogo 679-5198, Japan
6. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan