From XY Symmetry to Ising Symmetry in Successive Phase Transitions of Antiferroelectric Smectics

摘要

In order to clarify the mechanism of successive phase transitions in antiferroelectric smectics, a crossover from XY symmetry to Ising one is studied at finite temperature by introducing the XY model with competing second nearest neighbor interaction in the two-fold field. Global phase diagram shows how the phases with two types of symmetry coexist for the field smaller than a critical field and beyond this, the system exhibits essentially like a competing Ising model.