[Ren, Yi; Zhang, Z. H.; Cheng, Fang] Changsha Univ Sci & Technol, Dept Phys & Elect Sci, Changsha 410004, Hunan, Peoples R China.
[Zhou, Guanghui] Hunan Normal Univ, Dept Phys, Changsha 410081, Hunan, Peoples R China.
[Zhou, Guanghui] Hunan Normal Univ, Minist Educ, Key Lab Low Dimens Quantum Struct & Manipulat, Changsha 410081, Hunan, Peoples R China.
[Zhou, Guanghui] Hunan Normal Univ, Synerget Innovat Ctr Quantum Effects & Applicat H, Changsha 410081, Hunan, Peoples R China.