Dielectric Anomalies in Ferroelectric Nanostructures

Analytical derivations and first-principles-based computations are combined to establish the link between dielectric responses and thermal fluctuations of polarization in low-dimensional systems under any possible electrical boundary condition. It is proven that the analytical expression ͑in terms of polarization fluctuations͒ of the "external" dielectric susceptibility of a nanostructure, which is defined as the polarization's response to an external field, is identical to that of the dielectric susceptibility in the bulk material. On the other hand, such expression has to be modified for the "internal" dielectric susceptibility of a nanostructure that characterizes the response of the polarization to the total internal field. Such modification originates from the existence of the depolarizing field, and involves the depolarizing coefficients, as well as the degree of screening of the polarization-induced surface charges.

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“…Additional investigations about negative response functions can be found in Ref. 38. Let us rewrite Eq.…”

Section: Simulationsmentioning

confidence: 99%

Relation between dielectric responses and polarization fluctuations in ferroelectric nanostructures

2007

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“…Another example of ferroelectrics with inhomogeneous polarization is the nanoscale ferroelectrics in which polarization inhomogeneity is introduced by the presence of a surface or interface. In this case a strong depolarizing field due to uncompensated surface charge gives rise to many intriguing phenomena such as unusual domain patterns [29][30][31] and non-vanishing internal electric fields [32][33][34][35][36] which can be used in photovoltaic applications [37][38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

“…From an electrostatic point of view, the variation of polarization leads to an appearance of an electric field, which is often referred to as the depolarizing, or internal, field. The depolarizing field in ferroelectrics is typically quite large [36] owing to the large values of spontaneous polarization [34]. As a result, its effect on the polarization is dramatic and believed to cause the polarization offsets in polarization-graded ferroelectrics [43], unusual domain patterns in nanoscale ferroelectrics [29] and enhanced photocurrent [15,42] in ferroelectric thin films.…”

Section: Introductionmentioning

confidence: 99%

Depolarizing field in temperature-graded ferroelectrics from an atomistic viewpoint

Zhang

Ponomareva

2013

New J. Phys.

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An atomistic approach for computing the depolarizing, or internal, electric field in materials with inhomogeneous polarization is developed. Application of the approach for studying the depolarizing fields in technologically important (Ba 0.7 Sr 0.3 )TiO 3 ferroelectric alloy with temperature gradients has revealed the intrinsic features of these fields as well as their role in the establishment of polarization gradients. It is found that the depolarizing fields are inhomogeneous and can be tailored to yield both zero and non-vanishing potential drops. Such findings could pave the way to unusual thermoelectric materials, photovoltaics and locally conducting materials, all of which are at the frontier of current research. Contents

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“…[1][2][3] Upon shrinking of the characteristic lengths down to nanometers, the FE dipoles may align in vortexlike domain structures as evolved from the 90°-striped domain patterns. Ferroelectrics in nanometer scale substantially deviate from their bulk counterparts in terms of domain structures and consequently FE property.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo simulation on the size effect in ferroelectric nanostructures

Xue

Gao

Liu

2009

Journal of Applied Physics

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Monte Carlo simulation of ferroelectric domain structure and applied field response in two dimensionsThe ferroelectric domain structures in a two-dimensional square lattice with different lattice sizes under a set of finite boundary conditions ͑zero dipole and clamped strain on lattice boundaries͒ are investigated using Monte Carlo simulation, based on the Landau phenomenological model. Given the finite boundary conditions, the ferroelectric domain structure evolves gradually from the 90°-striped pattern into the single-vortex pattern with reducing lattice size. When the finite boundary conditions apply only onto one-dimensional boundaries, as an approach to the case of thin films, the single-domain pattern is favored with reducing lattice size. The physics underlying the evolution of domain structures with varying lattice size is discussed.

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Dielectric Anomalies in Ferroelectric Nanostructures

Cited by 34 publications

References 21 publications

Relation between dielectric responses and polarization fluctuations in ferroelectric nanostructures

Relation between dielectric responses and polarization fluctuations in ferroelectric nanostructures

Depolarizing field in temperature-graded ferroelectrics from an atomistic viewpoint

Monte Carlo simulation on the size effect in ferroelectric nanostructures

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