  We report on the observation of a spin texture in a cold exciton gas in a
GaAs/AlGaAs coupled quantum well structure. The spin texture is observed around
the exciton rings. The observed phenomena include: a ring of linear
polarization, a vortex of linear polarization with polarization perpendicular
to the radial direction, an anisotropy in the exciton flux, a skew of the
exciton fluxes in orthogonal circular polarizations and a corresponding
four-leaf pattern of circular polarization, a periodic spin texture, and
extended exciton coherence in the region of the polarization vortex. The data
indicate a transport regime where the spin polarization is locked to the
direction of particle propagation and scattering is suppressed.
