Observation of a periodic array of flux-closure quadrants in strained ferroelectric PbTiO ₃ films

Abstract

Nanoscale ferroelectrics are expected to exhibit various exotic domain configurations, such as the full flux-closure pattern that is well known in ferromagnetic materials. Here we observe not only the atomic morphology of the flux-closure quadrant but also a periodic array of flux closures in ferroelectric PbTiO3 films, mediated by tensile strain on a GdScO3 substrate. Using aberration-corrected scanning transmission electron microscopy, we directly visualize an alternating array of clockwise and counterclockwise flux closures, whose periodicity depends on the PbTiO3 film thickness. In the vicinity of the core, the strain is sufficient to rupture the lattice, with strain gradients up to 10(9) per meter. Engineering strain at the nanoscale may facilitate the development of nanoscale ferroelectric devices.

Domain structures of ferroelectric films under different electrical boundary conditions

“…The widths of some domains are greater and some domain walls of adjacent domains become narrower. Recently, Tang et al 35 reported their experimental results about multi-vortices domain structures in PbTiO 3 film. They observed periodic and regular vortices domains in PbTiO 3 thin film when it was sandwiched by SrTiO 3 layers.…”

Atomic Mapping of Domain Configurations in Ferroelectric Thin Films

“…We have grown a number of PbTiO 3 /SrTiO 3 multilayered samples on orthorhombic GdScO 3 (110) substrates by pulsed laser deposition (PLD), using a Lambda Physik LPX 305i KrF (λ=248 nm) excimer laser. We observe the as-grown epitaxial PbTiO 3 /SrTiO 3 multilayer films in which the electric dipoles at domain-walls of ferroelectric PbTiO 3 are characterized by means of aberration-corrected scanning transmission electron microscopy (AC-STEM) [2][3][4][5][6]. We also rationalize the experimental observation via phase-field modeling [3].…”

“…We directly visualize an alternating array of clockwise and counter-clockwise flux-closures, whose periodicity depends on the PbTiO 3 film thickness. In the vicinity of the core, the strain is sufficient to rupture the lattice, with strain gradients up to 10 9 /m [5]. We also observe a 3D polarization texture of a four-fold flux closure domain.…”

The Interactions of Ferroelectric Domain Walls and Crystallographic Defects in the PbTiO3 Films

“…Although some theoretical calculations about the interaction between dislocations and 90°/180° domain walls have been conducted [3], they are not revealed so far in experiments. Particularly, the atomic details and the local strain interactions were unattainable in these methods.With the recent development of aberration-corrected (scanning) transmission electron microscope (Cs-(S)TEM), direct mapping of domain walls at the atomic scale becomes possible [4][5][6][7]. For instance, systematic investigations on 180° domain wall and 90° charged domain wall in tetragonal ferroelectrics reveal the different width and polarization characteristics at these domain walls compared to the uncharged one.…”

“…With the recent development of aberration-corrected (scanning) transmission electron microscope (Cs-(S)TEM), direct mapping of domain walls at the atomic scale becomes possible [4][5][6][7]. For instance, systematic investigations on 180° domain wall and 90° charged domain wall in tetragonal ferroelectrics reveal the different width and polarization characteristics at these domain walls compared to the uncharged one.…”