Spin Texture in a Cold Exciton Gas
  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. 
A.A. High, A.T. Hammack, J.R. Leonard, Sen Yang, L.V. Butov, T.   Ostatnicky, A.V. Kavokin and A.C. Gossard
cond-mat.mes-hall