Chiral melting of the Si(113) (3×1) reconstruction

The results of an x-ray-scattering study of the (3×1)-to-disordered phase transformation of the Si(113) surface are reported. A continuous commensurate-solid to incommensurate-fluid transformation at ${\mathit{T}}_{\mathit{c}}$=950±40 K is observed. At the transformation, the reconstructed layer becomes unaxially incommensurate along the cubic (11¯0) direction (x direction). It remains commensurate along the (332¯) direction (y direction). Critical scattering shows power-law behavior over nearly two decades of reduced temperature [t=(T-${\mathit{T}}_{\mathit{c}}$)/${\mathit{T}}_{\mathit{c}}$] with exponents β¯=0.66±0.05 for the incommensurability (ε), ${\nu }_{\mathit{x}}$=0.65±0.07 for the inverse correlation length in the incommensurate direction (${\mathrm{\kappa }}_{\mathit{x}}$), ${\nu }_{\mathit{y}}$=1.06±0.07 for the inverse correlation length in the commensurate direction (${\mathrm{\kappa }}_{\mathit{y}}$), and γ=1.56±0.13 for the susceptibility (χ). Below ${\mathit{T}}_{\mathit{c}}$ the variation of the square of the order parameter, proportional to the peak intensity at the commensurate position (${\mathit{I}}_0$), varies with an exponent 2β=0.22±0.04.