Multicomponent Order Parameter: Crystallographic Phase Transitions

Alexander Umantsev, Fayetteville State University

Abstract

As we stated in Chap. 8, a phase transition is associated with symmetry change. Many cases of phase transitions cannot be described adequately by a scalar order parameter. They require an OP of more complicated structure, e.g., a “vector.” An example in the previous chapter, to some extent, is a case in point. Another example is a crystallographic transition, i.e., symmetry change in a crystalline solid. In this section we will consider only equilibrium characteristics of such transformations, which is well described by the Landau theory of phase transitions.