[1] Natl Inst Adv Ind Sci & Technol, Nanoelect Res Inst, Tsukuba, Ibaraki, Japan
[2] Univ Tokyo, Inst Ind Sci, Tokyo, Japan
[3] Tohoku Univ, Inst Mat Res, Sendai, Miyagi, Japan
[4] Natl Inst Mat Sci, Int Ctr Mat Nanoarchitecton WPI MANA, Tsukuba, Ibaraki, Japan