1. Department of Applied Science for Electronics and Materials, Kyushu University, Fukuoka 816-8580, Japan
2. Core Research for Evolutionary Science and Technology, Japan Science and Technology Agency, Tokyo 102-0076, Japan
3. The Ultramicroscopy Research Center, Kyushu University, Fukuoka 819-0395, Japan
4. Department of Materials Physics, Nagoya University, Nagoya 464-8603, Japan
5. Institute for Technical Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
6. Department of Advanced Materials Science and Engineering, Faculty of Engineering Sciences, Kyushu University, Fukuoka 816-8580, Japan