Switching time dispersion and retention of bistable states in Langmuir-Blodgett ferroelectric films

Гейвандов, А. Р.; Palto, S. P.; Yudin, S. G.; Blinov, L. M.

doi:10.1134/1.1787081

Cited by 20 publications

(19 citation statements)

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“…6.11 and coincides with (6.5) [41]. The results reported in [41], which were obtained with a continuous LB film by local voltage application using an AFM tip, are consistent with previous results, which were obtained with flat aluminum electrodes on continuous LB films [20,40]. In all three studies, the qualitative nature of switching changed from extrinsic to intrinsic at a critical thickness in the range 15 to 18 nm, which is in reasonable agreement with the predictions of Gerra et al [42].…”

Section: The Homogeneous Switching In the Ultrathin Ferroelectric Copsupporting

confidence: 93%

“…The results of [20] are confirmed in the independent paper [40], where the switching of (PVDF-TrFE 70:30) with thickness 20 ML was measured by Merz method, Fig. 6.7.…”

Section: The Homogeneous Switching In the Ultrathin Ferroelectric Copsupporting

confidence: 75%

“…In other words, the switching mechanism of a such ultrathin films could be homogeneous and has true threshold field, called intrinsic coercive field E int C or intrinsic voltage V int C , below which switching is impossible. Just after the discovery of the ultrathin 1 nm ferroelectric films, the kinetics theory of homogeneous switching was developed by means of Landau-GinzburgDevonshire (LGD) theory and experimentally verified for ultrathin ferroelectric copolymer films [8,20,40,41,48]. The rate of homogeneous switching, obtained from LGD phenomenology for the first order ferroelectrics, has a true threshold intrinsic coercive field E int C and corresponding voltage V int C and exhibits critical dependence on the applied voltage V, as follows:…”

Section: The Homogeneous Intrinsic Switching In the Batiomentioning

confidence: 99%

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Switching Kinetics at the Nanoscale

Fridkin

Ducharme

2013

Ferroelectricity at the Nanoscale

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From the time of domain discovery, the switching kinetics of ferroelectric crystals and thin films has been explained by the domain nucleation and domain dynamics. The domain theory of Kolmogorov-Avrami-Ishibashi (KAI) [1][2][3][4][5][6] successfully explained the switching kinetics of ferroelectric crystals and even thin films with thickness l C 50 nm.A ferroelectric crystal maintains a permanent electric polarization that can be repeatedly switched between two stable states by an external electric field, thus exhibiting a polarization-electric field hysteresis loop ( Fig. 1.3). The hysteresis loops are characterized by the magnitude of the remanent polarization achieved after saturation with a large electric field and by the magnitude of the coercive field, the minimum value of the electric field necessary to reverse, or switch, the polarization state. This coercive field Ec, obtained from LGD mean field theory (Eqs. 4.3, 4.4), is called the intrinsic coercive field, because the switching is homogeneous. From the all previous studies of the kinetics of switching in ferroelectric crystals, it has been apparent that switching is almost invariably an extrinsic process involving the inhomogeneous nucleation of small domains of reversed polarization, usually initiated at crystal boundaries or defects, and subsequent growth of these domains to fill the crystal [7]. Nucleation-limited extrinsic switching is characterized by an exponential increase in the switching rate with increased temperature and electric field, characteristic of an activated process, and is usually achieved with external fields in the range 0.1-50 MV/m. Strictly speaking, extrinsic switching does not have a true threshold coercive field because the activation of nucleation permits switching at arbitrarily small fields, given enough time, but switching experiments are typically carried out with an ac field and so the apparent coercive field is actually a function of frequency. Accordingly this coercive field is called extrinsic.In the absence of nucleation, switching an ideal ferroelectric crystal with uniform polarization requires the application of an enormous coercive field. We call this the intrinsic switching mechanism, and the associated threshold field the intrinsic coercive field [8,9]. The expected value of the intrinsic coercive field is of order 100 MV/m in most ferroelectrics [9]. Intrinsic switching does not occur below the intrinsic coercive field because the constituent crystal dipoles are highly V. Fridkin and S. Ducharme, Ferroelectricity at the Nanoscale, NanoScience and Technology,

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Section: The Homogeneous Switching In the Ultrathin Ferroelectric Copsupporting

confidence: 93%

“…The results of [20] are confirmed in the independent paper [40], where the switching of (PVDF-TrFE 70:30) with thickness 20 ML was measured by Merz method, Fig. 6.7.…”

Section: The Homogeneous Switching In the Ultrathin Ferroelectric Copsupporting

confidence: 75%

Section: The Homogeneous Intrinsic Switching In the Batiomentioning

confidence: 99%

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Switching Kinetics at the Nanoscale

Fridkin

Ducharme

2013

Ferroelectricity at the Nanoscale

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“…The homogeneous LGD switching (switching without domains) was never observed before 1998 neither in crystal nor in the films. The results, obtained in [7,[10][11][12][13], led many authors [1] to the conclusion, that this polymer ferroelectric switching is possibly an exception. But recently the same results were obtained for laser-epitaxial BaTiO 3 films with thickness l* = 3-10 nm [14].…”

mentioning

confidence: 97%

“…Ferroelectric films with l ≈ l*, investigated in [7], have shown switching. Later in subsequent papers [10][11][12][13] have been shown, that copolymer films with thickness l* equal by the order of value to the critical size of domain nucleus reveal homogeneous switching. The homogeneous LGD switching (switching without domains) was never observed before 1998 neither in crystal nor in the films.…”

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confidence: 99%

Scaling of the coercive field in ferroelectrics at the nanoscale

Gaynutdinov

Minnekaev

Mitko³

et al. 2013

Jetp Lett.

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Density functional study of α–β phase transition of polyvinylidene difluoride

Heo¹,

Kim²,

Shin³

et al. 2012

Physica Rapid Research Ltrs

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We perform density functional calculations to investigate structural and dynamical properties of crystalline polyvinylidene difluoride (PVDF) associated with the transition from α to β phase. We examine the change of the conformational energy and the corresponding structure of each phase depending on the lattice parameters of the orthorhombic crystalline structure. From this information, we construct the path that connects the point where the α phase is most stable to the point where the β phase is most stable, and identify the sub‐ region in the lattice parameter space where α and β phases have the same energy. In this sub‐region, we locate the point which gives the lowest conformation energy for both α and β phases, and examine the behaviour of the lowest energy profile and corresponding change of intermediate structures as the conformation of the PVDF chain transforms from α phase to β phase. Finally we perform ab‐initio molecular dynamics simulations and analyse the characteristic dynamics associated with transition from α to β phase. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Switching time dispersion and retention of bistable states in Langmuir-Blodgett ferroelectric films

Cited by 20 publications

References 13 publications

Switching Kinetics at the Nanoscale

Switching Kinetics at the Nanoscale

Scaling of the coercive field in ferroelectrics at the nanoscale

Density functional study of α–β phase transition of polyvinylidene difluoride

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