Electrostatic Coupling and Local Structural Distortions at Interfaces in Ferroelectric/Paraelectric Superlattices

Zubko, Pavlo; Jecklin, Noemie Marie; Torres‐Pardo, Almudena; Aguado‐Puente, Pablo; Gloter, Alexandre; Lichtensteiger, Céline; Junquera, Javier; Stéphan, Odile; Triscone, Jean‐Marc

doi:10.1021/nl3003717

Cited by 117 publications

(140 citation statements)

References 51 publications

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“…And polar vortices in superlattices demonstrated in Ref. [13] have been directly observed recently in PbTiO 3 /SrTiO 3 superlattices [14], although non uniform domain morphologies were first studied using an electrostatic model in Ref. [15].…”

Section: Introductionmentioning

confidence: 93%

Enhanced Energy Storage with Polar Vortices in Ferroelectric Nanocomposites

et al. 2017

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Nanocomposites of ferroelectric ceramic filler and polymer matrix show considerable promise as high energy storage dielectric capacitors. However, the influence of microstructure of the ferroelectric filler on the electric energy storage performance in the nanocomposite has not been quantitatively studied, yet it is a key element in understanding the methods employed to improve the performance of capacitors. We demonstrate an innovative strategy to enhance the energy storage density with topological vortex structures in nanocomposites. Using three dimensional phase field calculations, we show that multi-vortex structures can exist in ferroelectric nanowires without charge defects or free charges at the interface between the filler and matrix. The switching behavior of the topological structure (vortex and anti-vortex pair) under external electric field is calculated in nanocylinder wires. The small remnant polarization and very narrow hysteresis loop due to the vortex structure in the nanocomposites can lead to a large enhancement of energy density, as high as 5 J/cm 3 compared to 1-2 J/cm 3 for commercial capacitors, and high energy storage efficiency (over 95%) at a relatively low electric field of 140 MV/m.

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Section: Introductionmentioning

confidence: 93%

Enhanced Energy Storage with Polar Vortices in Ferroelectric Nanocomposites

et al. 2017

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“…omains [82], usually assumed to be dictated only by the electrostatic boundary conditions, and may help explain the large coherence lengths for the domains observed in PbTiO 3 /SrTiO 3 superlattices [81,83]. polarization, rotations of the TiO 6 octahedra, strain, strain gradients and depolarizing fields in a fully self-consistent manner, yield somewhat lower, but still sizable estimates [19].…”

Section: Polarization-induced Bendingmentioning

confidence: 99%

Flexoelectric Effect in Solids

Zubko

Catalán

Tagantsev

2013

Annu. Rev. Mater. Res.

918

663

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Piezoelectricity-the coupling between strain and electrical polarization, allowed 2 Zubko, Catalan, Tagantsev by symmetry in a restricted class of materials-is at the heart of many devices that permeate our daily life. Since its discovery in the 1880's by Pierre and Jacques Curie, the piezoelectric effect has found use in everything from submarine sonars to cigarette lighters. By contrast, flexoelectricity-the coupling between polarization and strain gradients, allowed by symmetry in all materials-was largely overlooked for decades since its first proposal in the late 1950's, due to the seemingly small magnitude of the effect in bulk. The development of nanoscale technologies, however, has renewed the interest in flexoelectricity, as the large strain gradients often present at the nanoscale can lead to dramatic flexoelectric phenomena. Here we review the fundamentals of the flexoelectric effect, discuss its presence in many nanoscale systems, and look at potential applications of this fascinating phenomenon. The review will also emphasize the many open questions and unresolved issues in this developing field.

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“…It is therefore crucial that the ferroelectric layer thickness is held fixed as it determines the periodicitiy of the ferroelectric domain structure and thus the ferroelectric transition temperature and the domain-wall contribution to the measured dielectric constant. All superlattices within a series must also be in the same regime of electrostatic coupling, which places a lower limit on the STO layer thickness at around 3-4 unit cells 36 .…”

Section: Calculation Of the Individual Layer Permittivitiesmentioning

confidence: 99%

Negative capacitance in multidomain ferroelectric superlattices

Zubko¹,

Wojdeł²,

Hadjimichael³

et al. 2016

Nature

339

318

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*These authors contributed equally to this work.The stability of the spontaneous electrical polarisation characteristic of ferroelectrics is fundamental to a multitude of their current applications, ranging from the simple electrical cigarette lighter to non-volatile random access memories 1 . Yet, the technological potential of these materials is far from being exhausted as research on nanoscale ferroelectrics reveals their properties to be profoundly different from those in bulk, giving rise to fascinating new phenomena with exciting prospects for future 2 devices 2-4 . As ferroelectrics become thinner, maintaining a stable polarisation becomes increasingly challenging. On the other hand, intentionally destabilising this polarisation can cause the effective electrical permittivity of a ferroelectric to become negative 5 , enabling it to behave as a negative capacitance when integrated in a heterostructure.Negative capacitance has been garnering increasing attention following the realisation that it could be exploited to overcome fundamental limitations on the power consumption of field effect transistors 6 . Experimentally, however, demonstrations of this phenomenon are still contentious 7 . The prevalent interpretations based on homogeneous polarisation models are difficult to reconcile with the expected strong tendency for domain formation 8,9 , while the effect of domains on negative capacitance has received surprisingly little attention 5,10-12 . Here we report the observation of negative capacitance in a model system of multidomain ferroelectric-dielectric superlattices across a wide range of temperatures, in both the ferroelectric and paraelectric phases. Using a phenomenological model we show that domain-wall motion not only gives rise to negative permittivity but can also enhance, rather than limit, its temperature range. Furthermore, our first-principles-based atomistic simulations provide detailed microscopic insight on the origin of this phenomenon, identifying the dominant contribution of near-interface layers and paving the way for its future exploitation.Negative capacitance (NC) has its origins in the imperfect screening of the spontaneous polarisation 5,10,13,14 . Imperfect screening is intrinsic to any semiconductor-ferroelectric or even metal-ferroelectric interfaces because of their finite effective screening lengths 15,16 .Alternatively, it can be engineered in a controlled manner by deliberately inserting a dielectric layer of relative permittivity ߳ ௗ between the ferroelectric and the electrodes as suggested by Salahuddin and Data 6 and shown in Fig. 1a. The physical separation of the 3 ferroelectric bound charge from the metallic screening charges creates a depolarizing field inside the ferroelectric, destabilizing the polarisation and lowering the ferroelectric transition temperature. The effect of the dielectric layer can be understood by considering the free energy of the bilayer capacitor with the usual assumption of a uniform polarisation ܲ (see Methods). Below the bulk transitio...

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Electrostatic Coupling and Local Structural Distortions at Interfaces in Ferroelectric/Paraelectric Superlattices

Cited by 117 publications

References 51 publications

Enhanced Energy Storage with Polar Vortices in Ferroelectric Nanocomposites

Enhanced Energy Storage with Polar Vortices in Ferroelectric Nanocomposites

Flexoelectric Effect in Solids

Negative capacitance in multidomain ferroelectric superlattices

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