[5] Gu S J, Tian G S and Lin H Q 2007 Chin. Phys. Lett.
24 2737

[6] Shan C J et al 2006 Acta. Phys. Sin. 55 1585
(in Chinese)

[7] Liu T K 2007 Chin. Phys. 16 3396

[8] Lu D M and Zheng S B 2007 Chin. Phys. Lett. 24
596.

[9] Pang C Y and Li Y L 2006 Chin. Phys. Lett. 23
3145

[10] Zhai X Y and Tong P Q 2007 Chin. Phys. Lett.
24 2475

[11] Wu Y and Machta J 2005 Phys. Rev. Lett. 95
137208

[12] Wang X G 2001 Phys. Rev. A 64 012313

[13] Zhang G F and Li S S 2005 Phys. Rev. A 72
034302

[14] Zhao J Z et al 2003 Phys. Rev. Lett. 90
2072041

[15] Chutia S et al 2006 Phys. Rev. B
73 241304

[16] Fu H C et al 2002 J. Phys. A 35 4293

Li S B and Xu J B 2005 Phys. Lett. A 334 109

[17] Cheng W W et al 2007 Physica E 39 150

[18] Xin R, Song Z and Sun C P 2005 Phys. Lett. A
342 30

[19] Huang Z et al 2004 Phys. Lett. A 322 137

[20] Osenda O et al 2003 Phys. Rev. A 67 062321

[21] Shan C J et al 2008 Chin. Phys. 17 (in press)

[22] Osterloh A et al 2002 Nature 416 608

[23] Zhang G F 2007 Phys. Rev. A 75 034304

[24] Gurkan Z N and Pashaev O K 2007 arxiv: 0705.0679v1

[25] Dzyaloshinsky I et al 1958 J. Phys. Chem. Solids
4 241

Moriya T 1960 Phys. Rev. Lett. 4 228

[26] Lieb E, Schultz T and Mattis D 1961 Ann. Phys.
60 407

[27] Wick G C 1950 Phys. Rev. 80 268

[28] Wooters W K 1998 Phys. Rev. Lett. 80 2245