[1] School of Physics, Shandong University, Jinan 250100, China;
[1] School of Physics, Shandong University, Jinan 250100, China;
[1] School of Physics, Shandong University, Jinan 250100, China;
[1] School of Physics, Shandong University, Jinan 250100, China;
[1] School of Physics, Shandong University, Jinan 250100, China;
[1] School of Physics, Shandong University, Jinan 250100, China;
[2] State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China;