Department of Physics Weinan Normal University Wei'nan 714099 China;
Department of Physics Weinan Normal University Wei'nan 714099 China;
Department of Physics Weinan Normal University Wei'nan 714099 China;
Department of Physics Weinan Normal University Wei'nan 714099 China;
Department of Physics Weinan Normal University Wei'nan 714099 China;
School of Physics Xi'an Jiaotong University Xi'an 710049 China;
School of Physics Xi'an Jiaotong University Xi'an 710049 China;