Novel melting transition in a two-dimensional stripe-domain system

The melting transition of the two-dimensional stripe-domain phase of bromine layers intercalated into graphite has been investigated by high-resolution x-ray diffraction. The transition is characterized by the progressive vanishing of successive harmonics so that near melting the density is described by a two-dimensional sine wave. Surprisingly, the sine-wave order parameter is best characterized by the power-law form, &, with ${\mathrm{\eta }}_1$ evolving continuously from 0.04 to ∼2.0 through melting.