3-domain spin dynamics in an ultracold Rb-87 gas

We investigate the motion of spin domain walls in a nondegenerate trapped pseudo-spin-1/2 Bose gas. Using customizable optical potentials, we initialize structures of three domains separated by narrow domain walls and study the short-time wall motion in a spin-independent potential. Our experiments reveal the strong influence of the local imbalance of spin-up and spin-down atoms in the domains on the domain-wall trajectories. This "spin impurity," particularly manifested by the presence of transverse spin in the middle domain, leads to increased spin-exchange collisions and induces spin currents, thereby driving wall motion. We also study the effects of trap symmetry on the wall trajectories by creating both symmetric and asymmetric domains.