Paraelectric and ferroelectric order in two-state dipolar fluids

TL;DR

This paper uses Monte Carlo simulations to study phase transitions in two-state dipolar fluids, revealing a transition from nonpolar to polar phases and eventual ferroelectric crystal formation, with significant dielectric anomalies.

Contribution

It introduces a detailed simulation study of phase transitions in two-state dipolar fluids, including a mean-field model explanation.

Findings

Second order transition from nonpolar to polar phase

Dielectric susceptibility increases by three orders of magnitude

Formation of ferroelectric crystal from paraelectric phase

Abstract

Monte Carlo simulations are used to examine cooperative creation of polar state in fluids of two-state particles with nonzero dipole in the excited state. With lowering temperature such systems undergo a second order transition from nonpolar to polar, paraelectric phase. The transition is accompanied by a dielectric anomaly of polarization susceptibility increasing by three orders of magnitude. The paraelectric phase is then followed by formation of a nematic ferroelectric which further freezes into an fcc ferroelectric crystal by a first order transition. A mean-field model of phase transitions is discussed.