Soluble model for X-ray scattering from CDWs with dislocations

Abstract
Charge density waves in constraint geometry experience stresses which can easily exceed a plastic threshold. Relevant situations include macroscopic crystal defects, surface strain, kinks at the surface, junctions and their edges, field effect. The stress is resolved by creation of dislocations which can be observed by modern scattering techniques of space resolved diffraction. We present theoretical considerations on the appearance and the role of enforced dislocations in such situations. We perform precise calculations for a special model of the surface scattering at presence of an array of dislocation lines which are assumed to be well aligned, submerged at the same depth but spaced randomly. The results recover such generally important features as nonsymmetry of intensity profiles I(q) and competition between their single and double peak shapes.