1. Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
2. Department of Physics Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
3. Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA
4. College of Science and Laboratory of Materials Design and Quantum Simulation, Changchun University, ChangChun 130022, China
5. National Lab of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, PR China