In one-dimensional electron systems, cooperative effects are expected to cause very specific electronic instabilities. Atomic nanowires, formed via self-organized growth on semiconductor surfaces, represent viable physical realizations for the study of such fascinating one-dimensional quantum states. The system in the focus of this work, Si(553)-Au, is created by Au adsorption on a stepped silicon substrate. It features two different chain types, interspersed with each other: Au chains on the terraces, and Si step edges that are subject to the formation of spin chains. By combining high-resolution scanning tunneling microscopy and local tunneling spectroscopy, the authors reveal the complex interplay between the two distinct wire architectures. The interaction is effectively “one-way” in that the Si step edges respond to the Au chains, but not vice versa. As a consequence, the symmetry of the system is lowered as the parity of the Si chains is broken. This fundamental effect creates two different configurations of chains with opposite directionality.
