1. National Research Center for Geoanalysis, 26 Baiwanzhuang, Beijing 100037, China
2. Materials Analysis Station, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba,
Ibaraki 305-0047, Japan
3. Center for Condensed Matter and Materials Physics, Department of
Physics, Beihang University, Beijing 100191,
China
4. Graduate School of
Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan