Spontaneous Crystallization of Skyrmions and Fractional Vortices in the   Fast-rotating and Rapidly-quenched Spin-1 Bose-Einstein Condensates
  We investigate the spontaneous generation of crystallized topological defects via the combining effects of fast rotation and rapid thermal quench on the spin-1 Bose-Einstein condensates. By solving the stochastic projected Gross-Pitaevskii equation, we show that, when the system reaches equilibrium, a hexagonal lattice of skyrmions, and a square lattice of half-quantized vortices can be formed in a ferromagnetic and antiferromagnetic spinor BEC, respetively, which can be imaged by using the polarization-dependent phase-contrast method. 
S.-W. Su, C.-H. Hsueh, I.-K. Liu, T.-L. Horng, Y.-C. Tsai, S.-C. Gou   and W. M. Liu
cond-mat.quant-gas