[1] Seoul Natl Univ, Ctr Semicond Nanorods, Natl Creat Res Initiat, Seoul 151747, South Korea
[2] Seoul Natl Univ, Dept Phys & Astron, Seoul 151747, South Korea
[3] Los Alamos Natl Lab, Ctr Integrated Nanotechnol, Los Alamos, NM 87545 USA
[4] POSTECH, Dept Chem, Pohang 790784, Gyeongbuk, South Korea
[5] Univ Calif Los Angeles, Dept Mat Sci & Engn, Los Angeles, CA 90024 USA
[6] CNRS, Inst Neel, F-38042 Grenoble, France
[7] Univ Grenoble 1, F-38042 Grenoble, France