1. Department of Physics, Duke University, Durham, NC 27708, USA.
2. Department of Physics and Astronomy, Appalachian State University, Boone, NC 28607, USA.
3. Department of Applied Physics, University of Tokyo, Bunkyo-ku,Tokyo, 113-8656, Japan.
4. Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan.
5. Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama 351-0198, Japan.
6. PRESTO, Japan Science and Technology Agency, Kawaguchi-shi, Saitama 332-0012, Japan.