1. College of Science and Technology, Nihon University, Chiba 274-8501, Japan
2. Department of Physics, Okayama University, Okayama 700-8530, Japan
3. Laboratoire Structures, Propriétés et Modélisation des Solides, CentraleSupélec, CNRS, Université Paris-Saclay, Châtenay-Malabry 92295, France
4. Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
5. Laboratoire Léon Brillouin, CE Saclay CNRS-UMR12, Gif-Sur-Yvette 91991, France