1. Department
of Physics, Xiangtan University, Xiangtan, Hunan 411105, China
2. Department
of Physics, The University of Texas at Austin, Austin, Texas 78712, United States
3. School
of Mechanical Engineering, Xiangtan University, Xiangtan, Hunan 411105, China
4. College
of Physics and Information Science, Hunan Normal University, Changsha 410081, China
5. International
Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
6. Key Laboratory
of Computational Physical Sciences and Department of Physics, Fudan University, Shanghai 200433, China