A General and Unified Theory of the Homophone Sequences of Transitions in Which the Soft Modes are Doubly Degenerate

Abstract

Of homophone systems of phase transitions, especially those in which the soft modes are doubly degenerate are investigated in a general and unified way upon the basis of the considerations in the preceding paper [K. Aizu: J. Phys. Soc. Japan 38 (1975) 1592]. It is found that three general forms are possible for their pedigrees. It is clarified what character of the prototypic phase and the soft modes are responsible for this essential differentiation of pedigrees. The number of all situations of a ferroic phase of each rank in each general pedigree is determined. Illustrations are carried out with some cases where the space group of the prototypic phase and the transformation property of the soft modes are specified.