Affiliation: | a Department of Quantum Matter, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan b Toyo Advanced Technologies Co. Ltd., 5-3-38 Ujina-Higashi, Minami-ku, Hiroshima 734-8501, Japan |