Landau-Lifshitz Analysis for Stepped Surfaces

摘要

Consider phase transitions on stepped surfaces. The Landau Lifshitz rules are used as criteria for determining those (commensurate) superlattice structures that are allowed, i.e., may be reached by continuous phase transitions. The problem is reduced to an essentially two dimensional case which allows one to make use of the results of Rottman. Tables of all possible allowed (commensurate) structures (with scalar order parameters) are given, along with a step by step procedure for determining whether a given superlattice structure on a given stepped surface is allowed. Some examples are treated in detail. It is also determined that all allowed transitions are in either the Ising or X-y with cubic anisotropy universality classes. The effects of random fields generated by non-uniform terrace width distributions are also mentioned. Keywords: Surface Phase Transitions; Super Lattices; Landau Theory; Reprints.