Quantum paraelectric phase of SrTiO3 from first principles

Dongbin Shin,Angel Rubio,Shunsuke A Sato,Christian Schäfer,Simone Latini,Hannes Hübener,Umberto De Giovannini

doi:10.1103/physrevb.104.l060103

Abstract

We demonstrate how the quantum paraelectric ground state of ${\mathrm{SrTiO}}_{3}$ can be accessed via a microscopic ab initio approach based on density functional theory. At low temperature the quantum fluctuations are strong enough to stabilize the paraelectric phase even though a classical description would predict a ferroelectric phase. We find that accounting for quantum fluctuations of the lattice and for the strong coupling between the ferroelectric soft mode and lattice elongation is necessary to achieve quantitative agreement with experimental frequency of the ferroelectric soft mode. The temperature dependent properties in ${\mathrm{SrTiO}}_{3}$ are also well captured by the present microscopic framework.

Highlights

We demonstrate how the quantum paraelectric ground state of SrTiO3 can be accessed via a microscopic ab initio approach based on density functional theory
We find that accounting for quantum fluctuations of the lattice and for the strong coupling between the ferroelectric soft mode and lattice elongation is necessary to achieve quantitative agreement with experimental frequency of the ferroelectric soft mode
The decisive role played by quantum fluctuations for the temperature dependent competition between the ferro- and paraelectric phases has been confirmed by quantum Monte Carlo calculations with an effective Hamiltonian for phenomenologically strained SrTiO3 [32,33] as well as for other materials [25,26]

Summary

Introduction

We demonstrate how the quantum paraelectric ground state of SrTiO3 can be accessed via a microscopic ab initio approach based on density functional theory. The quantum paraelectric phase is widely accepted as the explanation for the low temperature behavior of SrTiO3 [3,34,35], the ground state of the quantum paraelectric phase and the frequency of the FES mode at low temperature have not yet been described by a microscopic theory.

Results

Conclusion