1. Graduate School of Engineering and Science, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan
2. Center for Advanced High Magnetic Field Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
3. Low Temperature Center, Osaka University, Toyonaka, Osaka 560-0043, Japan
4. Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan
5. Department of Materials Science and Engineering, Tokyo Institute of Technology, Yokohama 226-8502, Japan
6. Faculty of Science, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan