[1] Huaibei Normal Univ, Anhui Key Lab Energet Mat, Coll Phys & Elect Informat, Huaibei 235000, Peoples R China
[2] Chinese Acad Sci, Hefei Inst Phys Sci, Key Lab Mat Phys, Hefei 230031, Anhui, Peoples R China
[3] Chinese Acad Sci, Hefei Inst Phys Sci, Anhui Key Lab Nanomat & Nanotechnol, Hefei 230031, Anhui, Peoples R China
[4] Univ Sci & Technol China, Hefei Natl Lab Phys Sci Microscale, Hefei 230026, Anhui, Peoples R China