1. International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan
2. Research Network and Facility Services Division, NMR Station, National Institute for Materials Science, 3-13, Sakura, Tsukuba, Ibaraki 305-0003, Japan
3. Solid-State NMR Group, Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, 3-13, Sakura, Tsukuba, Ibaraki 305-0003, Japan
4. Department of Condensed Matter Physics Graduate School of Science, Hokkaido University, Kita-10 Nishi-8 Kita-ku, Sapporo 060-0810, Japan