1. Department of Quantum Matter, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
2. Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
3. Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
4. Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
5. Institute for Advanced Materials Research, Hiroshima University, Higashi-Hiroshima 739-8530, Japan