  The macroscopically ordered exciton state (MOES) - a periodic array of beads
with spatial order on a macroscopic length - appears in the external exciton
rings at low temperatures below a few Kelvin. Here, we report on the
experimental study of the interaction in the MOES. The exciton PL energy varies
in concert with the intensity along the circumference of the ring, with the
largest energy found in the brightest regions. This shows that the MOES is
characterized by the repulsive interaction and is not driven by the attractive
interaction.
