Spin excitation spectra of spin–orbit coupled bosons in an optical lattice*
Li Ruo-Yana), He Liangb), Sun Qingc)†, Ji An-Chunc)‡, Tian Guang-Shana)
       
(a) Phase diagram in the Mott insulating regime. The solid lines are the mean-field results. The filled areas with colors are the stable regions, while the white areas are the unstable ones under the spin-wave fluctuations. (b) Spin configurations of the XY -FM, commensurate 4×1 spiral spin, 3×3 SkX, and 2×2 VX phases.