Department of Physics, School of Sciences, Hebei University of Science and technology, Shijiazhuang 050018;
Department of Physics, School of Sciences, Hebei University of Science and technology, Shijiazhuang 050018;
School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009;
Department of Physics, School of Sciences, Hebei University of Science and technology, Shijiazhuang 050018;
Department of Physics, School of Sciences, Hebei University of Science and technology, Shijiazhuang 050018;