1. Faculty of Engineering, Yokohama National University 1 , 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan
2. Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science 2 , 1-2-1 Sengen, Tsukuba 305-0047, Japan
3. Graduate School of Fine Arts, Tokyo University of the Arts 3 , 12-8 Ueno-koen, Taito, Tokyo 110 8714, Japan
4. Graduate School of Science and Engineering, Yamagata University 4 , 4-3-16 Jyonan, Yonezawa 992 8510, Japan