Fluctuations, Coulomb effects, and long-range order in incommensurate charge-density-wave structures

The effect of Coulomb interactions between long-wavelength fluctuations in various incommensurate charge-density-wave (CDW) structures is investigated, using a Ginzburg-Landau form for the free-energy functional of the system. For the case of a CDW in a quasi-one-dimensional metal, it is found that these interactions can largely cancel the disruptive effect that impurity-induced fluctuations would otherwise have on long-range order in the system. Quasi-Bragg peaks with a singular, non-Lorentzian line shape are then expected to be observed in elastic-scattering experiments.