1. Faculty of Materials and Energy, Southwest University, Chongqing 400715, China
2. College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400047, China
3. Shenzhen Key Laboratory of Special Functional Materials, Shenzhen University, Shenzhen 518060, China
4. Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA