1. School of Physics
and Engineering, Henan University of Science and Technology, Luoyang
City, Henan Province 471023, P. R. China
2. Hefei National Laboratory for Physical
Sciences at the Microscale, iChEM (Collaborative Innovation Center
of Chemistry for Energy Materials), CAS Key Laboratory of Mechanical
Behavior and Design of Materials, School of Chemistry and Materials
Science, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
3. National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, P. R. China