Atomistic view of impurities interacting with a quasi-one-dimensional charge density wave

Abstract

Atomistic details of the interaction of impurities with quasi-one-dimensional charge density wave (CDW) are revealed by scanning tunneling microscopy. Oxygen and pentacene adsorbates are utilized as strongly and weakly interacting impurities, respectively, on the well-known CDW state of the In atomic wire array on the Si(111) surface. Distinct CDW pinning configurations are identified for oxygen impurities with different atomic structures, indicating the strong pinning. The governing role of local strain field for the strong pinning is elucidated. In contrast, a few different pinning configurations occur for a unique adsorption structure of pentacene indicating a weak pinning. Pentacene molecules commonly induce characteristic phase shifts, which readily couple with other phase defects, in particular, solitons in order to avoid interwire phase misfits. This work provides the mechanism and methodology for the atomic scale control over phases, solitons, and domain boundaries of CDW.