1. Department of Physics, Oakland University, Rochester, Michigan 48309-4401, USA
2. Department of Materials Science and Engineering, Hubei University, Wuhan 430062, China
3. College of Electrical and Information Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China
4. Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115, USA
5. Novgorod State University, Veliky Novgorod 173003, Russia