1. State
Key Laboratory for Mesoscopic Physics and Collaborative Innovation
Centre of Quantum Matter, Peking University, Beijing 100871, China
2. Materials
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
3. Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
4. Department
of Material Science and Engineering, University of California at Berkeley, Berkeley, California 94720, United States