1. Department of Chemistry and Chemical Biology, Graduate School of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan
2. International Education and Research Center for Silicon Science, Graduate School of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan
3. R&D, Taiyo Yuden Co. Ltd., Takasaki, Gunma 370-0024, Japan