1. College of Physics and Information Science and Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of the Ministry of Education
2. Hunan Normal University
3. Changsha 410081, China
4. School of Materials Science and Engineering
5. Key Laboratory of Low-dimensional Materials and Application Technology (Ministry of Education)
6. Materials Research Center and Department of Applied Physics
7. The Hong Kong Polytechnic University
8. Hong Kong