Temperature-dependent dielectric and piezoelectric response of ferroelectrics from first principles

TL;DR

This paper introduces a first-principles method to calculate how dielectric and piezoelectric responses in ferroelectrics change with temperature, focusing on PbTiO3 and related materials near phase transitions.

Contribution

It develops a novel approach based on an effective Hamiltonian to predict temperature-dependent responses, emphasizing soft-mode contributions and providing real-space interpretations.

Findings

Method accurately captures response divergences near phase transitions.

Soft-mode contributions dominate the temperature dependence.

Differences between PbTiO3, BaTiO3, and KNbO3 are clarified.

Abstract

A method for the calculation of the temperature dependence of dielectric and piezoelectric responses, based on the use of a first-principles effective Hamiltonian, is described. Results are presented for the ferroelectric perovskite PbTiO3. While the method includes only the soft-mode contributions to the responses, it is argued to give a good description of the divergences or near-divergences of the response functions near the cubic-tetragonal transition. The expression of the response functions in terms of correlation functions is used to provide a real-space interpretation of the responses which clearly distinguishes between PbTiO3 and the related materials BaTiO3 and KNbO3.