1. a Department of Materials Science and Engineering , National Defense Academy , Yokosuka 239-8686 , Japan
2. b Synchrotron Radiation Research Center, Japan Atomic Energy Research Institute , Mikazuki-cho, Sayo-gun , Hyogo 679-5148 , Japan
3. c Condensed Matter Research Center and Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization , 1-1 Oho , Tsukuba 305-0801 , Japan
4. d Department of Physics, Faculty of Science , Nara Women's University , Nara 630-8263 , Japan