1. College of Physics, Qingdao University, Qingdao 266071, P. R. China
2. College of Electronics and Information, Qingdao University, Qingdao 266071, P. R. China
3. Department of Basic, Ma’anshan University, Ma’anshan 243100, P. R. China
4. Department of Material Science and Engineering, Department of Physics, Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China
5. College of Chemistry and Chemical Engineering, Shandong Sino-Japanese Center for Collaborative Research of Carbon Nanomaterials, Instrumental Analysis Center of Qingdao University, Qingdao University, Qingdao 266071, P. R. China
6. Paul M. Rady Department of Mechanical Engineering and Department of Physics, University of Colorado, Boulder, Colorado 80305-0427, United States
7. Weihai Innovation Research Institute, Qingdao University, Weihai 264200, P. R. China