Theoretical Lower Limit of Coercive Field in Ferroelectric Hafnia

Physical Review X, Journal Year: 2025, Volume and Issue: 15(2)

Published: May 6, 2025

The high coercive field (Ec) of hafnia-based ferroelectrics presents a major obstacle to their applications. ferroelectric switching mechanisms in hafnia that dictate Ec, especially those related domain nucleation the nucleation-limited-switching (NLS) model and domain-wall motion Kolmogorov-Avrami-Ishibashi (KAI) model, have remained elusive. We develop deep-learning-assisted multiscale approach, incorporating atomistic insights into critical nucleus, predict both NLS- KAI-type fields. theoretical NLS-type Ec values agree with previous experimental results as well our own measurements also exhibit correct thickness scaling for films between 3 20 nm. Combined investigations reveal giant Ec arises from ultrathin geometry, which confines NLS mechanism. lower limit Ec is 0.1 MV/cm arising mobile walls. activation achieve Ec supported by demonstration low 1 MV/cm 60 nm (HfO2)n/(ZrO2)n (n=3 unit cells) superlattices. These findings establish comprehensive framework understanding highlight potential geometry engineering low-Ec devices. Published American Physical Society 2025

Language: Английский

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Finite‐temperature properties of NbO2 ${\text{NbO}}_{2}$ from a deep‐learning interatomic potential

Materials Genome Engineering Advances, Journal Year: 2025, Volume and Issue: unknown

Published: May 6, 2025

Abstract Using first‐principles‐based machine‐learning potential, molecular dynamics (MD) simulations are performed to investigate the micro‐mechanism in phase transition of . Treating DFT results low‐ and intermediate‐temperature phases as training data deep‐learning model, we successfully constructed an interatomic potential capable accurately reproducing transitions from low‐temperature (pressure) high‐temperature regimes. Notably, our predict a high‐pressure monoclinic (>14 GPa) without treating its information set, consistent with previous experimental findings, demonstrating reliability potential. We identified Nb‐dimers key structural motif governing transitions. At low temperatures, displacements drive between (‐) phases, while at high Nb ions prone being equally distributed disappearance leads stabilization high‐symmetry phase. These findings elucidate dynamical mechanisms underlying properties highlight utility combining deep MD methods for studying complex metal oxides.

Language: Английский

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Compositional ordering driven morphotropic phase boundary in ferroelectric solid solutions

Physical review. B./Physical review. B, Journal Year: 2024, Volume and Issue: 110(5)

Published: Aug. 5, 2024

Ferroelectric solid solutions usually exhibit giant dielectric response and high piezoelectricity in the vicinity of morphotropic phase boundary (MPB), where structural transitions between rhombohedral tetragonal phases as a result composition or strain variation. Here, we propose compositional ordering driven MPB specified solutions. By preforming machine-learning potential-based molecular dynamics simulations on lead zirconate titanate, find transition from to with decrease ordering, leading temperature-ordering diagram. The can enhance magnitude comparable that at MPB. Finally, demonstrate mechanism is polarization rotation by external field. This work provides an additional degree freedom, design high-performance piezoelectric materials.

Language: Английский

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Finite-temperature properties of the antiferroelectric perovskite PbZrO3 from a deep-learning interatomic potential

Physical review. B./Physical review. B, Journal Year: 2024, Volume and Issue: 110(5)

Published: Aug. 21, 2024

The prototypical antiferroelectric perovskite ${\mathrm{PbZrO}}_{3}$ (PZO) has garnered considerable attention in recent years due to its significance technological applications and fundamental research. Many unresolved issues PZO are associated with large length- time-scales, as well finite temperatures, presenting significant challenges for first-principles density functional theory studies. Here, we introduce a deep-learnining interatomic potential of PZO, enabling investigation finite-temperature properties through large-scale atomistic simulations. Trained using an elaborately designed dataset, the model successfully reproduces number phases, particular, recently discovered 80-atom $Pnam$ phase ferrielectric $Ima2$ phase, providing precise predictions their structural dynamical properties. Using this model, investigated transitions multiple including $Pbam\text{/}Pnam, Ima2$, $R3c$, which show high similarity experimental observation. Our simulation results also highlight crucial role free energy determining low-temperature reconciling apparent contradiction: $Pbam$ is most commonly observed experiments, while theoretical calculations predict other phases exhibiting even lower energy. Furthermore, temperature range where thermodynamically stable, typical double polarization hysteresis loops antiferroelectrics were obtained, along detailed elucidation evolution during electric-field induced between nonpolar polar $R3c$ phases.

Language: Английский

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Quantum-Accurate Modeling of Ferroelectric Phase Transition in Perovskites from Message-Passing Neural Networks

The Journal of Physical Chemistry C, Journal Year: 2023, Volume and Issue: 127(42), P. 20890 - 20902

Published: Oct. 16, 2023

Graph-based message-passing neural networks (MPNNs) have been proposed to facilitate computational research on materials at the atomic scale, which represent chemical structure as an indirect graph and incorporate scheme learn interaction between atoms. Here, we employ MPNN framework investigate temperature-dependent structural phase transitions of perovskites. We take two prototypical ferroelectric perovskites, BaTiO3 PbTiO3, examples demonstrate application this approach. Our results show that well-trained models achieve a similar level accuracy density functional theory (DFT) calculations in terms both energy force, with few meV per atom. This fulfills requirement for investigating changes. By integrating calculators molecular dynamics simulations, investigated compounds reproduced their transition sequences. The simulated temperatures lattice parameters are comparable experimental or DFT results. Moreover, examined influence exchange–correlation functionals trained models. study demonstrates MPNN, can serve universal model, presents appealing approach treating properties

Language: Английский

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Mechanism of Antiferroelectricity in Polycrystalline ZrO₂

Advanced Functional Materials, Journal Year: 2024, Volume and Issue: 34(40)

Published: June 28, 2024

Abstract The size and electric field dependent induction of polarization in antiferroelectric ZrO 2 is the key to several technological applications that are unimaginable a decade ago. However, lack deeper understanding mechanism hinders progress. Molecular dynamics simulations polycrystalline , based on machine‐learned interatomic forces with near ab initio quality, shed light fundamental effect transition fields. Stress oxygen sublattice most important factor. so constructed allow calculation fields as function film thickness predict ferroelectricity at large thickness. simulation results validated electrical piezo response force microscopy measurements. clear interpretation properties double‐hysteresis loops well construction free energy landscape grains.

Language: Английский

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Assessing the Ubiquity of Bloch Domain Walls in Ferroelectric Lead Titanate Superlattices

Physical Review X, Journal Year: 2024, Volume and Issue: 14(4)

Published: Nov. 26, 2024

The observation of unexpected polarization textures such as vortices, skyrmions, and merons in various oxide heterostructures has challenged the widely accepted picture ferroelectric domain walls being Ising-like. Bloch components 180° PbTiO3 have recently been reported PbTiO3/SrTiO3 superlattices linked to wall chirality. While this opens exciting perspectives, ubiquity component remains be further explored. In work, we present a comprehensive investigation PbTiO3/SrTiO3 superlattices, involving combination first- second-principles calculations, phase-field simulations, diffuse scattering synchrotron-based x-ray scattering. Our theoretical calculations highlight that previously predicted PbTiO3/SrTiO3 might more sensitive boundary conditions than initially thought is not always expected appear. Employing for larger systems, develop method probe complex structure these via measurements. Through approach, investigate depolarization-driven rotation at walls. experimental findings, consistent with our predictions realistic periods, do reveal any signatures centers PbTiO3/SrTiO3 suggesting precise nature ultrathin PbTiO3 layers intricate deserves attention. Published by American Physical Society 2024

Language: Английский

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Ultrahigh oxygen ion mobility in ferroelectric hafnia

arXiv (Cornell University), Journal Year: 2023, Volume and Issue: unknown

Published: Jan. 1, 2023

Ferroelectrics and ionic conductors are important functional materials, each supporting a plethora of applications in information energy technology. The underlying physics governing their properties is motion, yet studies ferroelectrics often considered separate fields. Based on first-principles calculations deep-learning-assisted large-scale molecular dynamics (MD) simulations, we report ferroelectric-switching-promoted oxygen ion transport HfO$_2$, wide-band-gap insulator with both ferroelectricity conductivity. Applying unidirectional bias can activate multiple switching pathways ferroelectric leading to polar-antipolar phase cycling that appears contradict classical electrodynamics. This apparent conflict resolved by the geometric-quantum-phase nature electric polarization carries no definite direction. Our MD simulations demonstrate bias-driven successive transitions facilitate ultrahigh mobility at moderate temperatures, highlighting potential combining conductivity for development advanced materials technologies.

Language: Английский

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Latent space active learning with message passing neural network: The case of HfO2

Physical Review Materials, Journal Year: 2024, Volume and Issue: 8(10)

Published: Oct. 11, 2024

Language: Английский

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Topological phase transitions in perovskite superlattices driven by temperature, electric field, and doping

Physical review. B./Physical review. B, Journal Year: 2024, Volume and Issue: 110(21)

Published: Dec. 27, 2024

Language: Английский

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