Spinodals and Domain Instabilities in Ionically-compensated Ferroelectric Films
Abstract
A ferroelectric surface in contact with an ionic or molecular reservoir is intrinsically a ferroionic state in which polarization and compensating surface charge are thermodynamically coupled. Surface chemical compensation is known to control the magnitude and sign of ferroelectric polarization, yet the competing instability toward domain formation has usually been treated separately. Here we develop a static theory in which polarization, electrochemical surface charge, and finite-wave-vector domain formation are analyzed within a single thermodynamic framework for uniaxial polarization orientation. The central quantity is the differential chemical capacitance, which determines how strongly the surface charge can respond to a spatial modulation of polarization and therefore differs fundamentally from the equilibrium screening charge. We derive the homogeneous equation of state, the finite-wave-vector stability kernel, analytical domain-onset wavelengths and thickness scalings, and weakly nonlinear stripe and checkerboard solutions for both second- and first-order ferroelectrics. For a first-order transition, a finite-amplitude stripe state can become thermodynamically favorable before the homogeneous linear spinodal when the effective quartic coefficient is negative; this pre-spinodal window closes as the biased background polarization increases. Dense numerical phase maps confirm the analytical structure and show how chemical potential and film thickness reorganize weakly polar, monodomain, and polydomain states. Numerical analysis for BaTiO3 realization illustrates the corresponding temperature, oxygen-pressure, and thickness scales and identifies experimentally testable regimes in which chemical screening stabilizes the homogeneous state against the columnar 180° instability considered here or domain formation becomes the preferred route for depolarization-energy reduction.
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BibTeX
@misc{kalinin2026spinodals,
title = {{Spinodals and Domain Instabilities in Ionically-compensated Ferroelectric Films}},
author = {Sergei V. Kalinin},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.14111},
eprint = {2609.14111},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.14111},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Spinodals and Domain Instabilities in Ionically-compensated Ferroelectric Films
AU - Sergei V. Kalinin
PY - 2026
DA - 2026/09/12
PB - arXiv
DO - 10.48550/arxiv.2609.14111
UR - https://arxiv.org/abs/2609.14111
AB - A ferroelectric surface in contact with an ionic or molecular reservoir is intrinsically a ferroionic state in which polarization and compensating surface charge are thermodynamically coupled. Surface chemical compensation is known to control the magnitude and sign of ferroelectric polarization, yet the competing instability toward domain formation has usually been treated separately. Here we develop a static theory in which polarization, electrochemical surface charge, and finite-wave-vector domain formation are analyzed within a single thermodynamic framework for uniaxial polarization orientation. The central quantity is the differential chemical capacitance, which determines how strongly the surface charge can respond to a spatial modulation of polarization and therefore differs fundamentally from the equilibrium screening charge. We derive the homogeneous equation of state, the finite-wave-vector stability kernel, analytical domain-onset wavelengths and thickness scalings, and weakly nonlinear stripe and checkerboard solutions for both second- and first-order ferroelectrics. For a first-order transition, a finite-amplitude stripe state can become thermodynamically favorable before the homogeneous linear spinodal when the effective quartic coefficient is negative; this pre-spinodal window closes as the biased background polarization increases. Dense numerical phase maps confirm the analytical structure and show how chemical potential and film thickness reorganize weakly polar, monodomain, and polydomain states. Numerical analysis for BaTiO3 realization illustrates the corresponding temperature, oxygen-pressure, and thickness scales and identifies experimentally testable regimes in which chemical screening stabilizes the homogeneous state against the columnar 180° instability considered here or domain formation becomes the preferred route for depolarization-energy reduction.
ER -