Affiliation: | a Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan b Faculty of Engineering, Tohoku Gakuin University, Tagajo 985-8537, Japan c Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan d Faculty of Science and Technology, Ryukoku University, Otsu 520-2194, Japan e Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK |