1. Department of Physics, Kyoto University, Kyoto 606-8502, Japan
2. Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz–Zentrum Dresden–Rossendorf, D-01314 Dresden, Germany
3. Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
4. Institut für Festkörperphysik and Physikalisches Institut, Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany