Topological defects and inhomogeneous spin patterns induced by the quadratic Zeeman effect in spin-1 Bose-Einstein condensates.

We obtain analytically two kinds of inhomogeneous spin domain configurations endowed with time-dependent periodic domain walls in spin-1 Bose-Einstein condensate, which result from the positive and negative quadratic Zeeman effects, respectively. It is shown analytically that the topological defects are given by the unmagnetized atoms, at which the order parameter is of polar phase, but besides them, the order parameter is of axisymmetrybroken phase. The quadratic Zeeman effect can be tuned to induce the dynamical phase transition of the spin domain, and its sign can affect the topological structure of the spin pattern. These features arise from the axisymmetry breaking due to the pointwise-different population exchange between the sublevels determined uniquely by the quadratic Zeeman effects. The related experimental observations for the spin-187Rb and "Na condensates are also discussed. [ABSTRACT FROM AUTHOR]