EFFECT OF QUENCHED DISORDER ON A 2-DIMENSIONAL CLASSICAL WIGNER CRYSTAL

The effect of quenched random fields of different types on translational and orientational order and on dislocation melting of a 2D classical Wigner crystal is considered. Isotropic impurities interact only with the longitudinal plasma mode of a 2D Wigner solid and do not destroy, in the harmonic phonon approximation, the 2D translational order for potentials of the lattice-impurity interaction decaying as r-1 or faster. Charged Coulomb impurities embedded in a 2D crystal, if their concentration does not exceed the critical value, may induce the low-temperature reentrant melting. Ionized remote donors destroy the solid phase, unless charge fluctuations are strongly suppressed. For the substrate-generated anisotropic random pinning force there is only a short-range crystalline order, though the sizes of the crystalline regions may be arbitrarily large.