Modeling ferroelectric properties in systems of induced andpermanent dipoles

摘要

In earlier studies we reported on Monte Carlo simulations ofdielectric properties in systems of permanent or induced dipolesconsidering electrostatic interactions. The calculations are expandednow to systems composed of induced and permanent dipoles with the finalpurpose to model ferroelectric properties in structures like BaTiO₃. In a first step a dipole chain with permanent dipoles (Ti-ionsmoving in double well potentials) and induced dipoles (O-ions) inalternating order is considered referring to the [001] crystal directionin BaTiO₃. The calculation yields a hysteresis loop of thepolarization, a Curie-Weiss law, a temperature dependent remanentpolarization, and a spontaneous polarization. A second system refers tothe (200) plane of BaTiO₃. Besides a hysteresis of thepolarization with a temperature dependent remanent polarization, we findspontaneous ferroelectric domains with an uniform polarization. Typicalferroelectric properties arise if permanent and induced dipoles areinvolved in the interaction process