Polydomain structures in ferroelectric and ferroelastic epitaxial films

Abstract

A review of theoretical models, phase field modeling and experimental studies of domain structures in epitaxial films is presented. The thermodynamic theory of such domain structures is presented within the macroscopic thermo-mechanical framework. The theory allows for the evaluation of the main parameters of the domain structure using the energy minimization approach applied to the energy of elastic interactions. For homophase (polytwin) films, the thermodynamic theory provides a quantitative tool that can be used to estimate domain fractions in the film and the type of domain structure architecture. For heterophase films, the theory describes (a) the conditions under which two-phase structures can be obtained in epitaxial films, and (b) the phase and domain fractions in these films. The thermodynamic theory can also be used to describe the extrinsic contributions from domain structures to the functional properties of epitaxial ferroelectric films. The review of phase field modeling demonstrates that computational results reproduce the predictions of the thermodynamic theory. It is also shown that the phase field modeling that utilizes the energy minimization procedure for elastic and interfacial energies can be used to predict domain morphology for the films with two-phase structures produced either by phase transformation or through the co-deposition of immiscible phases. The experimental data presented in the review validate predictions of the thermodynamic model and the results of phase field modeling.

Crystal Orientations Dependent Polarization Reversal in Ferroelectric PbZr0.2Ti0.8O3 Thin Films for Multilevel Data Storage Applications

“…[13] Also presence of domain walls can be identified, for [135]/[111] 28.56° PZT shown in Figure 2a, the marked region of c/c domain wall exhibit clear contrast of piezoresponse in 2a-d is that polydomain structure exhibit island like domain configurations, which is in contrast from the expected PZT tetragonal polydomain structure with regularly shaped domain variants based on c/a domain structure. [14] In single crystal PZT thin films, three domain variants c/a 1 /a 2 are normally observed in a cubic-tetragonal transformation, where c, a 1 , and a 2 are the domains that point along [001], [100], and [010], respectively. [14] Such type of regular polydomain structure can be controlled by varying substrate strain, film thickness, orientation, and composition.…”

“…[14] In single crystal PZT thin films, three domain variants c/a 1 /a 2 are normally observed in a cubic-tetragonal transformation, where c, a 1 , and a 2 are the domains that point along [001], [100], and [010], respectively. [14] Such type of regular polydomain structure can be controlled by varying substrate strain, film thickness, orientation, and composition. [14][15][16][17] The typical expected polydomain structure based on misfit are two domain c/a/c/a stripe shaped, and three domain cellular or hierarchical (second-order) polydomain structures based on distribution of c and a domains.…”

Mechanical-force-induced non-local collective ferroelastic switching in epitaxial lead-titanate thin films

“…Such a collective domain switching process is strongly related to the potential energy barrier between the two domain-structure variants. Based on Landau-type phenomenological theory for polydomain structures 38 , the calculated Landau free-energy densities of the a 1 / a 2 and c/a domain patterns are equal at the critical strain of ~0.46% at 300 K; however, at high temperature, such as 500 K, are about −22 MJ/m 3 and −19 MJ/m 3 , respectively, with an energy difference of only ~3 MJ/m 3 (Supplementary Fig. 13).…”

“…More specifically, 40-nm-thick, (001)-oriented films of PbTiO 3 grown on DyScO 3 (110) O (where the O denotes orthorhombic indices) experience a compressive strain that drives the formation of traditional c / a domain structures, while films grown on NdScO 3 (110) O substrates with large tensile strain exhibit a 1 / a 2 domain structures, and films grown on SmScO 3 (110) O substrates with a strain state between that of DyScO 3 and NdScO 3 exhibit a coexistence of both c / a and a 1 / a 2 domain variants 36 . In effect, epitaxial strain can be used to place this material on the brink of a transition between domain-structure variants and is an ideal route by which to explore the potential for large responses and collective effects 37,38 .…”

Superdomain dynamics in ferroelectric-ferroelastic films: Switching, jamming, and relaxation

“…a micron. [98] Finally, in the context of period doubling and tripling, Roytburd et al [98] have recently stressed in a comprehensive review on ferroelastics, that there may be situations in which two different kinds of domains are simultaneously present in quasi-equilibrium, due to boundary conditions, and these do not involve nonlinear doubling or tripling. And Jang's laboratory has shown that the Landau-Lifshitz-Kittel law can fail in nanostructures due to surface layers.…”