1. Faculty of Engineering, Shinshu University 4-17-1 Wakasato, Nagano, 380-8553, Japan
2. Institute of Carbon Science and Technology, Shinshu University, 4-17-1 Wakasato, Nagano, Japan
3. Department of Physics, Tohoku University, Sendai, 980-8578, Japan
4. The Department of Physics and Mathematics, Division of Science, Arts and Technology, Universidad Iberoamericana, Avenida Prolongación Paseo de la Reforma 880, Santa Fé 012100, DF, México
5. Departamento de Ciencia e Ingeniería de Materiales e Ingeniería Química, Escuela Politécnica Superior, Universidad Carlos III de Madrid, Avenida Universidad 30, 28911 Leganés, Madrid, Spain
6. Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307