Laboratory;
of;
Materials;
Physics,;
Institute;
of;
Solid;
State;
Physics,;
Chinese;
Academy;
af;
Sciences,;
Hefei;
230031,;
China;
of;
Physics;
and;
Electronics;
Information,;
Huaibei;
Normal;
University,;
Huaibei;
235000,;
China;