1. College of Material Science and Engineering & State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620, China
2. State Key laboratory of Crystal Materials, Shandong University, Jinan 250100, China
3. Department of Physics, National University of Singapore, 117542, Singapore
4. Department of Physics, University of Science and Technology of China, Hefei 230026, China