Defect-mediated condensation of a charge density wave

Symmetry, dimensionality, and disorder play a pivotal role in critical phen omena. The atomic imaging capabilities of the scanning tunneling microscope were used to directly visualize the interaction between charge density osc illations and Lattice defects in a two-dimensional charge density wave (CDW ) system, point defects act as nucleation centers of the CDW, which, as the temperature is Lowered, results in the formation of pinned CDW domains tha t are separated by atomically abrupt charge boundaries. Incomplete freezing of substitutional disorder at low temperature indicates a novel CDW-mediat ed hopping of pinning centers.