[1] E China Normal Univ, Dept Phys, Shanghai 200062, Peoples R China
[2] E China Normal Univ, Key Lab Opt & Magnet Resonance Spect, Shanghai 200062, Peoples R China
[3] Univ Paris 07, Lab Phys Theor Mat Condensee, F-75251 Paris, France
[4] Hong Kong Baptist Univ, Dept Phys, Hong Kong, Hong Kong, Peoples R China
[5] Hong Kong Baptist Univ, Ctr Nonlinear Studies, Hong Kong, Hong Kong, Peoples R China
[6] Univ Houston, Dept Phys, Houston, TX 77204 USA