“…By trapping all Zeeman states of an atomic species in an optical trap, these spinor BEC possess a wealth of phenomena not found in single-component condensates, including spin vortex [6], spin textures [7,8], domain wall structure [9,10], and spontaneous demagnetization dynamics [11,12]. It is well known that the sign of atomic spin-exchange interaction determines the ground state property of spin-1 condensate, and leads to different quantum phases [3,13,14]. Moreover, under an applied external magnetic field, the spontaneous symmetry breaking in a 87 Rb spinor BEC has recently been observed [7].…”