1. International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
2. Research and Services Division of Materials Data and Integrated System, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
3. Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8568, Japan
4. Center for Advanced Intelligence Project, RIKEN, Chuo, Tokyo 103-0027, Japan
5. Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, U.K.