Monte carlo simulations of the pseudo-spin ising model for hydrogen-bonded ferroelectrics

Abstract

Monte Carlo (MC) simulations are performed for hydrogen-bonded-type ferroelectrics by using a three dimensional pseudo-spin Ising model. The pseudo-spin interaction strengths V and U are related to the Slater-Takagi energy parameters ɛ0 and ɛ1 via U = (ɛ0 − ɛ1)/2 and V = (2ɛ1 − ɛ0)/4. The phase transition temperature and the longitudinal and transverse dielectric constants are calculated as functions of interaction ratio R = − U/V, in the range of R from 0 to 1. According to the MC simulations, the longitudinal dielectric constant exhibits a ferroelectric phase transition while the transverse constant exhibits behavior associated with an antiferroelectric transition. The transverse dipole moments obtained from a mean-field approximation and the domain motion in the microscopic structure are discussed in view of hydrogen-ion bombardment experiments on KH2PO4 crystals.