1. Institute
of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
2. Electron
Microscopy Laboratory, School of Physics, and Center for Nanochemistry, Peking University, Beijing 100871, China
3. Collaborative
Innovation
Center of Quantum Matter, Beijing 100871, China
4. Nanostructures
Research Laboratory, Japan Fine Ceramics Center, Atsuta, Nagoya 456-8587, Japan
5. World
Premier International Research Center Initiative for Advanced Institute
for Materials Research, Tohoku University, Sendai 980-8577, Japan