1. Max-Planck-Institut für Festköperforschung, 70569 Stuttgart, Germany
2. New York University, Shanghai 200120, China
3. NYU-ECNU
Institute of Physics at NYU Shanghai, Shanghai 200062, China
4. Department of Physics, Tohoku University, Sendai 980-8578, Japan
5. National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan