XING Liqian;CHEN Xichen, Institute of Physics, Academia Sinica, Beijing, ChinaYANG Gencang;ZHOU Yaohe, Northwestern Polytechnic University, Xi'an, ChinaGUO Zhenqi, Northwestern University, Xi'an, China XING Liqian, Postdoctoral, Institute of Physics, Academia Sinica, Beijing 100080, China