[1] Materials Science Division, Res. Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8550, Japan
[2] Japan Science and Technology Agency, 4-1-8 Honmachi, Kawaguchi, Saitama 332-0012, Japan
[3] Nanomaterials Laboratory, Natl. Inst. for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
[4] RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
[5] Technology Platform Research Center, SEIKO EPSON Corporation, 281 Fujimi, Nagano 399-0293, Japan