Fast Molecular-Dynamics Simulation for Ferroelectric Thin-Film Capacitors Using a First-Principles Effective Hamiltonian

TL;DR

This paper introduces a rapid molecular-dynamics simulation method based on a first-principles effective Hamiltonian to study ferroelectric thin-film capacitors, revealing how dead layers and other factors influence their properties.

Contribution

The study develops a fast simulation approach for ferroelectric thin films and demonstrates its effectiveness in analyzing the impact of dead layers, electrodes, and epitaxial constraints.

Findings

Dead layers significantly affect capacitor properties.

System cannot switch between polarized and striped states at low temperatures.

Hysteresis behavior depends on film thickness and electrode conditions.

Abstract

A newly developed fast molecular-dynamics method is applied to BaTiO3 ferroelectric thin-film capacitors with short-circuited electrodes or under applied voltage. The molecular-dynamics simulations based on a first-principles effective Hamiltonian clarify that dead layers (or passive layers) between ferroelectrics and electrodes markedly affect the properties of capacitors, and predict that the system is unable to hop between a uniformly polarized ferroelectric structure and a striped ferroelectric domain structure at low temperatures. Simulations of hysteresis loops of thin-film capacitors are also performed, and their dependence on film thickness, epitaxial constraints, and electrodes are discussed.