Electric-field dependent freezing in relaxor ferroelectrics

Pirc, R.; Kutnjak, Zdravko

doi:10.1103/physrevb.89.184110

Cited by 28 publications

(25 citation statements)

References 50 publications

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“…Here it is worth underlining that, due to the applied probing field strength (1 V/cm), entropy data describes the thermal evolution of the system without any coercive (several kV/cm) field effects on the PNR size and local structure, as reported by many authors [36,55,56]. The Fröhlich entropy analysis reported in Fig.…”

Section: B Order/disorder State Anisotropymentioning

confidence: 99%

“…The local ordering and crystalline symmetry of PNRs have been extensively investigated using various techniques, the principal being diffractometric [20,[27][28][29][30][31][32][33][34][35]. Results indicate that the behavior and response of PNR-hosting samples is strongly affected by disorder [5,13,21,36,37]. Several works have been devoted to investigating PNR dynamics in correspondence to the cubic-to-tetragonal phase transition using NMR and EXAFS techniques [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

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Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics

et al. 2016

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Using temperature-resolved dielectric spectroscopy in the range 25-320 K we investigate the macroscopic response, phase symmetry, and order/disorder states in bulk ferroelectric K 1−y Li y Ta 1−x Nb x (KLTN). Four longrange symmetry phases are identified with their relative transitions. Directional analysis of the order/disorder states using Fröhlich entropy indicates global symmetry breaking along the growth axis and an anisotropic dipolar effective thermodynamic behavior, which ranges from disordered to ordered at the same temperature for different directions in the sample. Results indicate that the macroscopic polarization, driven by nanosized polar regions, follows a microscopic perovskite eight-sites lattice model.

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Section: B Order/disorder State Anisotropymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics

et al. 2016

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“…Thus, a different mechanism capable of describing the VF relaxation in DGs is needed. One such example is the mechanism of cooperative rearrangement of dipolar clusters, [29] which has been briefly reviewed in [28] and will not be discussed here. So far, the electric field dependence of the VF temperature in DGs has not yet been studied.…”

Section: Introductionmentioning

confidence: 99%

“…A heuristic approach, based on some simple thermodynamic argument, was shown to lead to the percolation of PNRs and reproduce the VF relaxation time. [26,27] Recently, [28] a more rigorous thermodynamic formulation of the Samara mechanism has been proposed in the framework of a phenomenological model involving the Landau free energy of the medium in which the PNRs are embedded. The essential idea is that when the fourth-order Landau coefficient is negative ðb < 0Þ, the coupling between the medium and the PNR gives rise to a field-induced FE phase.…”

Section: Introductionmentioning

confidence: 99%

Freezing in relaxor ferroelectrics and dipolar glasses

Pirc

Kutnjak

2014

Phase Transitions

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A recently proposed semi-phenomenological model of freezing in relaxor ferroelectrics, based on the concept of polar nanoregions (PNRs) embedded in a polarizable medium, is reviewed. A generalized Landau-type free energy for the medium is discussed, where the medium polarization couples linearly to the PNR polarization. When the fourth-order Landau coefficient is negative (b < 0), the correlation radius r c , which measures the PNR size, depends on the temperature T and the applied field E. As T is lowered or E increased, r c increases and the volume of a cluster of PNRs grows until the percolation limit is reached. This leads to a generalized expression for the Vogel-Fulcher (VF) relaxation time with a fielddependent VF freezing temperature T 0 (E). The case b > 0, in which the percolation mechanism cannot be realized, is considered to be appropriate for dipolar glasses.

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“…[13][14][15][16][17][18][19][20][21][22] and references therein). Among its anomalous properties, the best known signature is perhaps the shift of the temperature T m , where the susceptibility as a function of temperature peaks, with frequency used in the measurement of the susceptibility.…”

Section: Introductionmentioning

confidence: 99%

Electric dipole sheets inBaTiO3/BaZrO3superlattices

Jiang¹,

Xu²,

Li³

et al. 2015

Phys. Rev. B

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We investigate two-dimensional electric dipole sheets in the superlattice made of BaTiO 3 and BaZrO 3 using first-principles-based Monte-Carlo simulations and density functional calculations. Electric dipole domains and complex patterns are observed and complex dipole structures with various symmetries (e.g. P ma2, Cmcm and P mc2 1 ) are further confirmed by density functional calculations, which are found to be almost degenerate in energy with the ferroelectric ground state of the Amm2 symmetry, therefore strongly resembling magnetic sheets. More complex dipole patterns, including vortices and anti-vortices, are also observed, which may constitute the intermediate states that overcome the high energy barrier of different polarization orientations previously predicted by Lebedev [1]. We also show that such system possesses large electrostrictive effects that may be technologically important.

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Electric-field dependent freezing in relaxor ferroelectrics

Cited by 28 publications

References 50 publications

Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics

Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics

Freezing in relaxor ferroelectrics and dipolar glasses

Electric dipole sheets inBaTiO3/BaZrO3superlattices

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