1. Nanomaterials Research Institute National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba 305‐8565 Japan
2. Interdisciplinary Graduate School of Engineering Sciences Kyushu University Fukuoka 816‐8580 Japan
3. Institute of Ion Beam Physics and Materials Research Helmholtz‐Zentrum Dresden‐Rossendorf 01328 Dresden Germany
4. Department of Applied Physics Aalto University P.O. Box 11100 Aalto 00076 Finland
5. Global Innovation Center (GIC) Kyushu University Fukuoka 816‐8580 Japan
6. The Institute of Scientific and Industrial Research (ISIR‐SANKEN) Osaka University Osaka 567‐0047 Japan