Ferroelectric properties of SrRuO3∕BaTiO3∕SrRuO3 ultrathin film capacitors free from passive layers

Kim, Y. S.; Jo, Ji Young; Kim, D. J.; Chang, Young Jun; Lee, Ju Hyoung; Noh, T. W.; Song, Tae Kwon; Yoon, Jong‐Gul; Chung, J.-S.; Baik, Sung Il; Kim, Y.-W.; Jung, C. U.

doi:10.1063/1.2174100

Cited by 60 publications

(45 citation statements)

References 22 publications

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“…In particular, the observation of a negligible intercept at one temperature 52 does not represent a convincing proof for the absence of "dead" layers in the capacitor. Indeed, such zero intercept may result from the mutual compensation of the positive and negative contributions to c t −1 ͑t → 0͒, but not from the zero interfacial capacitance c i .…”

Section: Discussionmentioning

confidence: 96%

Thickness dependence of intrinsic dielectric response and apparent interfacial capacitance in ferroelectric thin films

Pertsev

Dittmann

Plonka

et al. 2007

Journal of Applied Physics

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We studied theoretically the influence of the progressive strain relaxation and the depolarizing-field effect on the thickness dependence of the out-of-plane dielectric response of epitaxial ferroelectric thin films sandwiched between extended metal electrodes. The calculations show that the inverse of the measured capacitance varies with the film thickness almost linearly in the most part of the thickness range at the majority of temperatures. Extrapolation of this linear dependence to zero thickness usually gives considerable nonzero intercept even in the absence of nonferroelectric interfacial layers. Remarkably, such apparent “interfacial capacitance” in a certain temperature range becomes negative. The physical meaning of the effective dielectric constant, which can be extracted from the slope of the reciprocal capacitance thickness dependence, is also analyzed. The theoretical predictions are compared with the experimental data obtained for single-crystalline SrRuO3∕Ba0.7Sr0.3TiO3∕SrRuO3 and Pt∕Ba0.7Sr0.3TiO3∕SrRuO3 thin-film capacitors.

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Section: Discussionmentioning

confidence: 96%

Thickness dependence of intrinsic dielectric response and apparent interfacial capacitance in ferroelectric thin films

Pertsev

Dittmann

Plonka

et al. 2007

Journal of Applied Physics

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“…13,14 At this point, let us compare the observed E C values with the thermodynamic intrinsic limit using the LD model. To check for the possibility of homogeneous switching in our ultrathin films, we calculated E C using LD theory with the free energy density functional (Ĝ):…”

Section: -7mentioning

confidence: 99%

Coercive fields in ultrathin BaTiO3 capacitors

Kim

Noh

et al. 2006

Applied Physics Letters

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Thickness-dependence of coercive field (E C ) was investigated in ultrathin BaTiO 3 capacitors with thicknesses (d) between 30 and 5 nm. The E C appears nearly independent of d below 15 nm, and decreases slowly as d increases above 15 nm. This behavior cannot be explained by extrinsic effects, such as interfacial passive layers or strain relaxation, nor by homogeneous domain models. Based on domain nuclei formation model, the observed E C behavior is explainable via a quantitative level. A crossover of domain shape from a half-prolate spheroid to a cylinder is also suggested at d~ 15 nm, exhibiting good agreement with experimental results.

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“…The polar axis of the material is perpendicular to the film plane and the electrodes are 'real' meaning that the electric field penetrates into them, although only over tiny depths < 1Å. This is an adequate model for the perovskite ferroelectric films on a substrate with compressive strain, like BaTiO 3 /SrRuO 3 /SrTiO 3 (BTO/SRO/STO) [1][2][3][4][5] where the misfit strain drives the FE film into a uniaxial state. We supplement our analytical results with the relevant numerical estimates for BaTiO 3 (BTO), PbTiO 3 (PTO), and Pb(Zr 0.5 Ti 0.5 )O 3 (PZT) using the material constants available in the literature Incomplete screening of the depolarizing field by SrRuO 3 electrode leads to an absolute instability of a single domain state and formation of a sinusoidal domain structure when thickness of BaTiO 3 film is slightly above the minimal thickness compatible with ferroelectricity in this system [5][6][7] .…”

Section: Introductionmentioning

confidence: 99%

“…We shall also discuss this stability among other questions This makes sense because of several reasons. First, Pertsev and Kohlstedt performed numerical calculations using material constants for BaTiO 3 and Pb(Zr 0.5 Ti 0.5 )O 3 and the electrode parameters of SrRuO 3 while our results are analytical and apply to any material of the same symmetry. Moreover, our method applies to other symmetries as well.…”

Section: Introductionmentioning

confidence: 99%

Effects of anisotropic elasticity in the problem of domain formation and stability of monodomain state in ferroelectric films

Bratkovsky

Levanyuk

2011

Phys. Rev. B

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We study cubic ferroelectrics films that become uniaxial with a polar axis perpendicular to the film because of a misfit strain due to a substrate. The main present result is the analytical account for the elastic anisotropy as well as the anisotropy of the electrostriction. They define, in particular, an orientation of the domain boundaries and stabilizing or destabilizing effect of inhomogeneous elastic strains on the single domain state. We apply the general results to perovskite systems like BaTiO3/SrRuO3/SrTiO3 films and find that at least not far from the ferroelectric phase transition the equilibrium domain structure consists of the stripes along the cubic axes or at 45 degrees to them. We have also showed that in this system the inhomogeneous strains increase stability with regards to the small fluctuations of the metastable single domain state, which may exist not very close to the ferroelectric transition. The latter analytical result is in qualitative agreement with the numerical result by Pertsev and Kohlstedt [Phys. Rev. Lett. 98, 257603 (2007)], but we show that the effect is much smaller than those authors claim. We have found also that under certain conditions on the material constants, which are not satisfied in the perovskites but are not forbidden either, a checkerboard domain structure can be realized instead of the stripe-like one and that the polarization-strain coupling decreases stability of a single domain state instead of increasing it. The single domain state is metastable at certain large thicknesses and becomes suitable for memory applications at even larger thicknesses when the lifetime of the metastable state becomes sufficiently large.

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Ferroelectric properties of SrRuO3∕BaTiO3∕SrRuO3 ultrathin film capacitors free from passive layers

Cited by 60 publications

References 22 publications

Thickness dependence of intrinsic dielectric response and apparent interfacial capacitance in ferroelectric thin films

Thickness dependence of intrinsic dielectric response and apparent interfacial capacitance in ferroelectric thin films

Coercive fields in ultrathin BaTiO3 capacitors

Effects of anisotropic elasticity in the problem of domain formation and stability of monodomain state in ferroelectric films

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