1. Advanced Research Institute of Multidisciplinary Sciences (ARIMS), Beijing Institute of Technology, Beijing 100081, P. R. China
2. School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
3. School of Physics and State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, P. R. China
4. BIT Chongqing Institute of Microelectronics and Microsystems, Chongqing 400030, P. R. China