1. School of Physics Northwest University Xi'an 710069 China
2. National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base) in Shaanxi Province National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base Institute of Photonics & Photon‐Technology Northwest University Xi'an 710069 China
3. Northwest Institute for Nonferrous Metal Research Xi'an 710016 China
4. Institute of Modern Physics Northwest University Xi'an 710069 China