Affiliation: | a Center for Interdisciplinary Research, Tohoku University, Sendai 980-8578, Japan b Department of Physics, Graduate School of Engineering, Yokohama National University, Yokohama 240-8501, Japan c Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan d Department of Macromolecular Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan |