1. School of Physics Sun Yat-sen University Guangzhou 510275 P. R. China
2. School of Materials Science and Engineering Key Lab of Polymer Composite & Functional Materials Guangzhou Key Laboratory of Flexible Electronic Materials and Wearable Devices Sun Yat-sen University Guangzhou 510275 P. R. China
3. Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials School of Physics and Telecommunication Engineering South China Normal University Guangzhou 510006 P. R. China
4. Guangdong-Hong Kong Joint Laboratory of Quantum Matter Frontier Research Institute for Physics South China Normal University Guangzhou 510006 P. R. China
5. State Key Laboratory of Optoelectronic Materials and Technologies Sun Yat-sen University 510275 Guangzhou P. R. China