In-plane polarization states and their instabilities in polydomain epitaxial ferroelectric thin films

Koukhar, V. G.; Pertsev, N. A.; Waser, Rainer

doi:10.1063/1.1338960

Cited by 22 publications

(18 citation statements)

References 14 publications

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“…4), which is caused by the P 3 instability of this polarization configuration. 31 The analysis also shows that the inverse of the film permittivity, 1/ε 33 , varies with S m almost linearly in the stability range of the a 1 /a 2 /a 1 /a 2 structure. This…”

Section: Dielectric Response Of Epitaxial Pzt Filmsmentioning

confidence: 77%

Polarization states of polydomain epitaxialPb(Zr1−xTix)O3thin films and their dielectric properties

et al. 2006

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Ferroelectric and dielectric properties of polydomain (twinned) single-crystal Pb(Zr 1-x Ti x )O 3 thin films are described with the aid of a nonlinear thermodynamic theory, which has been developed recently for epitaxial ferroelectric films with dense laminar domain structures. For Pb(Zr 1-x Ti x )O 3 (PZT) films with compositions x = 0.9, 0.8, 0.7, 0.6, 0.5, and 0.4, the "misfit strain-temperature" phase diagrams are calculated and compared with each other. It is found that the equilibrium diagrams of PZT films with x ≥ 0.7 are similar to the diagram of PbTiO 3 films. They consist of only four different stability ranges, which correspond to the paraelectric phase, single-domain tetragonal ferroelectric phase, and two pseudo-tetragonal domain patterns. In contrast, at x = 0.4, 0.5, and 0.6, the equilibrium diagram displays a rich variety of stable polarization states, involving at least one monoclinic polydomain state. Using the developed phase diagrams, the mean out-of-plane polarization of a poled PZT film is calculated as a function of the misfit strain and composition. Theoretical results are compared with the measured remanent polarizations of PZT films grown on SrTiO 3 . Dependence of the out-of-plane dielectric response of PZT films on the misfit strain in the heterostructure is also reported.

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Section: Dielectric Response Of Epitaxial Pzt Filmsmentioning

confidence: 77%

Polarization states of polydomain epitaxialPb(Zr1−xTix)O3thin films and their dielectric properties

et al. 2006

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“…In the study of the effects of temperature, external mechanical loads and/or constraints on the phase diagram, the spontaneous polarization, the coercive field, the remanent polarization and the dielectric constant of ferroelectrics [3][4][5][6][7][8][9][10][11][12][13][14], thermodynamic theories are widely employed. For example, Oh and Jang [9] developed a two-dimensional thermodynamic model to investigate the effects of film stresses on the phase stability and various ferroelectric properties of epitaxially oriented Pb(Zr,Ti)O 3 thin films.…”

Section: Introductionmentioning

confidence: 99%

The effect of mechanical strains on the ferroelectric and dielectric properties of a model single crystal ? Phase field simulation

Wang

Chen

et al. 2005

Acta Materialia

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-The effect of applied mechanical strains on the ferroelectric and dielectric properties of a model single crystal is investigated using a phase field model based on the time-dependent Ginzburg-Landau equation, which takes both multiple-dipole-dipole-electric and -elastic interactions into account. The evolution of the ferroelectric domain structure is simulated at different temperatures and applied strains. The results show that the paraelectric/ferroelectric phase transition temperature linearly increases with the applied mechanical strain under mechanical clamping conditions. Analogous to the classical Ehrenfest equation, a thermodynamics equation is derived to describe the relationship between the transition temperature and the applied strain. The change in the domain structure with temperature under applied inequiaxial strains is different from that under applied equiaxial strains. The simulations also illustrate the changes in the coercive field, the remanent polarization and the nonlinear dielectric constant with the applied strain.

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“…22,23 Then, differences in nucleation of the domain walls along both in-plane directions could explain the observed differences in domain formation. Because during fast growth the sample is far from thermodynamic equilibrium (higher supersaturation), if the energy barrier for nucleation of domain walls kb was larger than that of the walls ka, the formation of the former walls would be hampered.…”

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confidence: 99%

Thickness scaling of ferroelastic domains in PbTiO3 films on DyScO3

Nesterov

Matzen

Magén

et al. 2013

Applied Physics Letters

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We report on the thickness dependence of the ferroelastic domains of PbTiO 3 films grown on (110)-DyScO 3 with low thicknesses (up to 240 nm), which fall outside the validity range of the square root law proposed by Roytburd. For slow-grown films, the data reveal the linear thickness dependence predicted by Pertsev and Zembilgotov, using a complete elastic description, while a 2/3 scaling exponent is found for fast-grown films. Extremely long domains running all through the samples have been observed in the latter case, compared to the short domains observed in slow-grown films. These differences are ascribed to the in-plane anisotropy for domain wall nucleation, which is likely caused by the anisotropic elastic modulus of the substrate. V C 2013 AIP Publishing LLC.[http://dx.doi.org/10.1063/1.4823536]The response of domains and domain walls crucially affects (and often determines) the dielectric properties and switching behavior of ferroelectrics. This is particularly important in thin films where the ferroelectric (180 ) and ferroelastic (non-180 ) domain walls are formed in order to comply with the stringent electrical (large depolarizing field) and mechanical (substrate mismatch strain and clamping) boundary conditions.The size of the domains increases with increasing film thickness as a result of the balance between the depolarizing field energy (for 180 domains) 1 or elastic strain energy (for non-180 domains) 2 and the domain wall formation energy. Thus, the thinner the films, the larger the domain wall density and the greater the influence of the walls on the ferroelectric properties. Moreover, domain walls break spatial symmetry and could add functionalities to the films when present in large amounts. 3 It is therefore most relevant to have good control of the domain formation and the density of domain walls. 4 Domain formation in ferroelectrics has been largely studied. 2,3,[5][6][7][8][9][10][11][12][13][14][15] In order to adapt to the substrate and to locally minimize the mismatch strain or the depolarizing field, the domains form in a periodic manner. 6,7 It is known that there is a quadratic dependence, W / d 1=2 , of the domain width (W) with the crystal thickness (b). In ferroelastic domains (typically 90 domains), this b 1=2 dependence is an approximation in the regime of d ) W. 2 For smaller thicknesses, a linear dependence has been predicted by Pertsev and Zembilgotov (P&Z), 8 but it has not been experimentally confirmed yet.In this paper we investigate the thickness dependence of the periodicity of ferroelastic 90 domains (a/c twins) in the lower thickness regime using PbTiO 3 films grown on DyScO 3 substrates. This combination is chosen because there is a very small lattice mismatch between film and substrate at the growth temperature. This minimizes the formation of defects during growth. As the films are cooled down strain develops and can be relaxed by forming a/c domains. The absence of defects allows these domains to form in a very periodic fashion. 13,16 Interestingly, when the films...

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In-plane polarization states and their instabilities in polydomain epitaxial ferroelectric thin films

Cited by 22 publications

References 14 publications

Polarization states of polydomain epitaxialPb(Zr1−xTix)O3thin films and their dielectric properties

Polarization states of polydomain epitaxialPb(Zr1−xTix)O3thin films and their dielectric properties

The effect of mechanical strains on the ferroelectric and dielectric properties of a model single crystal ? Phase field simulation

Thickness scaling of ferroelastic domains in PbTiO3 films on DyScO3

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