1. Department of Materials and Life Science, Faculty of Science and Technology, Shizuoka Institute of Science and Technology, Fukuroi, Shizuoka 437-0032, Japan
2. Department of Electrical, Electronic and Computer Engineering, Faculty of Engineering, Gifu University, Gifu 501-1193, Japan
3. KYOKUGEN, Center for Science and Technology Under Extreme Conditions, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
4. Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, U.S.A.