1. Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany.
2. State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China.
3. Collaborative Innovation Center of Quantum Matter, Beijing 100084, China.
4. Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany.
5. Department of Applied Physics and Quantum-Phase Electronics Center, University of Tokyo, Tokyo 113-8656, Japan.
6. Japan Science and Technology Agency, Precursory Research for Embryonic Science and Technology, Kawaguchi, Saitama 332-0012, Japan.
7. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
8. RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan.