Successive phase transitions of axial next-nearest-neighbor XY model with biquadratic interaction

Abstract

Successive phase transitions between ferro-, ferri- andantiferroelectric SmC^* phases are discussed using an axialnext-nearest-neighbor XY model with biquadratic interaction.Relative stability of several phases are determined by a mean fieldapproximation, and the phase diagrams are obtained for some biquadraticinteraction parameters.It is shown that this model with sufficiently strong biquadraticinteraction can reproduce the successive first order transitionscorresponding to what observed in experiments.