Exactly solvable model of uniaxial ferroelectrics

TL;DR

This paper presents an exactly solvable lattice model for uniaxial ferroelectrics, providing precise free energy expressions, accounting for thermal expansion, and refining Landau theory near the critical point.

Contribution

It introduces a new exactly solvable model for uniaxial ferroelectrics that accurately describes free energy and phase transition behavior, including corrections to traditional Landau expansion.

Findings

Derived asymptotically exact free energy expression at all temperatures.

Accounted for thermal expansion effects in the model.

Identified higher-order contributions in the external field term.

Abstract

An exactly solvable lattice model with infinite-range potential is applied to uniaxial ferroelectrics. Asymptotically exact expression for free energy as a function of an order parameter at any temperatures is obtained. Effect of thermal expansion of lattice unit cell is taken into account. The free energy expansion in powers of order parameter in the vicinity of critical point is presented. Corrections to Landau expansion are obtained. In particular, it is shown that summand with external field contains a contribution of higher powers over order parameter. Keywords: Lattice model, Free energy, Phase transition, Long-range interatomic potentials, Curie temperature, polarization PACS: 05.20.-y, 05.70.-a, 82.65.+r