1. Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan, College of Engineering, Department of Materials Science, Hosei University, 3-7-2 Kajino-machi, Koganei, Tokyo 184-8584, Japan, and Department of Electronics, Graduate School of Information Science and Electrical Engineering, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan