Commensurate-Incommensurate Phase Diagrams for Overlayers from a Helical Potts Model

Oversaturated layers such as krypton on graphite are represented by a triplet helical Potts model, incorporating domain walls and antiwalls, and their crossings and annihilations (dislocations). Renormalization-group treatment yields a disordered phase between commensurate and incommensurate phases, down to zero temperature. Coadsorption produces a first-order transition directly between the commensurate and incommensurate phases, in analogy to temper embrittlement.