1. Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), and Department of Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
2. National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
3. Department of Physics, University of York, Heslington, York YO10 5DD, U.K.