1. Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
2. Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501, Japan
3. Center for Elements Strategy Initiative for Structure Materials (ESISM), Kyoto University, Kyoto 606-8501, Japan
4. Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
5. Department of Materials Structure Science, School of High Energy Accelerator Science, SOKENDAI (The Graduate University for Advanced Studies), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
6. Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
7. Asahi Diamond Industrial Co., Ltd., Kawasaki, Kanagawa 213-0032, Japan