1. Department of Applied Physics, School of Physics, Xi’an Jiaotong University, Shaanxi 710049, People's Republic of China
2. MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi’an Jiaotong University, 710049, People's Republic of China
3. Laboratory of Nanostructure and Physics Properties, Key Laboratory for Quantum Information and Optoelectronic Quantum Devices of Shaanxi Province, School of Physics, Xi’an Jiaotong University, 710049, People's Republic of China