1. State Key Laboratory
for Mechanical Behavior of Materials, Xi’an Jiaotong University, Shannxi 710049, P. R. China
2. Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
3. School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China
4. Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, United States