Disordering of the (3×1) reconstruction on Si(113) and the chiral three-state Potts model

We have used high-resolution low-energy electron diffraction to study the disordering of the (3×1) reconstruction on Si(113). We find that the reconstruction disorders via a continuous transition at approximately 850 K. Above the transition temperature the positions of the superlattice diffraction beams shift away from their commensurate positions. The shift is proportional to the broadening of the beams, as expected from basic scaling arguments for a system in the chiral three-state Potts-model universality class. Also consistent with numerical studies of this class is the observation of critical exponents α, β, γ, and ν approximately equal to those of the pure three-state Potts model.