Department of Physics, Capital Normal University, Beijing 100048, china
Department of Physics, Capital Normal University, Beijing 100048, china
Department of Physics, Capital Normal University, Beijing 100048, china
Department of Physics, Capital Normal University, Beijing 100048, china
Department of Physics, Capital Normal University, Beijing 100048, china
Copyright © Feng Xue, Qiao-yan Dong, Xiao-bo Wang, Juan Chen, Shu-li He et al. This is
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