With scanning tunneling microscopy we have found that ordered phases in $\mathrm{P}\mathrm{b}/\mathrm{S}\mathrm{i}(111)$ are one of the best examples of the “devil’s staircase” phase diagram. Phases within a narrow coverage range ($1.2<\theta <1.3\mathrm{\text{monolayers}}$) are constructed with the rules similar to the ones found in theoretical models.

• Received 5 November 2002

DOI:https://doi.org/10.1103/PhysRevLett.90.216106