1. Department of Applied Physics, Xi’an University of Technology, Xi’an 710054, China
2. New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579, Miyagi, Japan
3. Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur, Chennai 603 203, Tamil Nadu, India
4. University of Science and Technology Beijing, Beijing 100083, China