Domain Bundle Boundaries in Single Crystal BaTiO₃ Lamellae: Searching for Naturally Forming Dipole Flux-Closure/Quadrupole Chains

Abstract

Naturally occurring boundaries between bundles of 90° stripe domains, which form in BaTiO(3) lamellae on cooling through the Curie Temperature, have been characterized using both piezoresponse force microscopy (PFM) and scanning transmission electron microscopy (STEM). Detailed interpretation of the dipole configurations present at these boundaries (using data taken from PFM) shows that in the vast majority of cases they are composed of simple zigzag 180° domain walls. Topological information from STEM shows that occasionally domain bundle boundaries can support chains of dipole flux closure and quadrupole nanostructures, but these kinds of boundaries are comparatively rare; when such chains do exist, it is notable that singularities at the cores of the dipole structures are avoided. The symmetry of the boundary shows that diads and centers of inversion exist at positions where core singularities should have been expected.

Super switching and control of in-plane ferroelectric nanodomains in strained thin films

“…These variants define micron-size 'superdomains' with a resultant inplane component of polarization along the [110] and [1][2][3][4][5][6][7][8][9][10] directions (see wide blue arrows). Similar patterns have been observed in single crystals of BaTiO 3 (lamellae and dots) 12,14,15 , dots of PZT 17 and lamellae of PZN-PT 18 , as well as in relatively thick PZT and PbTiO 3 films 38,39 , which included a fraction of domains with out-of-plane polarization and partial strain relaxation by dislocations. The DWs between superdomains are observed along both o1004 and o1104 crystallographic directions (see Fig.…”

“…First, very well-defined periodic domains with in-plane polarization are observed, with a periodicity along the o1104 directions and a domain period of 46 nm, in good agreement with the XRD results. No response has been observed while measuring the vertical PFM signal (except the usual contrast attributed to the cantilever buckling effect in the presence of in-plane polarization) 14 , confirming the absence of an out-of-plane component of polarization.…”

“…Within the PFM resolution, these two types of DWs between superdomains seem to be locally charged. However, McGilly et al 14 …”

Self-Similar Nested Flux Closure Structures in a Tetragonal Ferroelectric

“…Additional internal depolarizing fields caused within a mesoscale flux closure object should not be present. Equally, the formation of flux closure-quadrupole chains is not a structural necessity -a shift in the registry of the stripe domains on either side of the 180 o superdomain junction by half a period would allow simple zig-zag 180 o domain walls to form instead; after all, these rather simpler superdomain boundary structures have been previously observed in BaTiO 3 [21].…”

“…Instead, the flux closure object is split into two junction points where domain boundaries intersect. As noted in previous work [21], the reluctance of the system to form a single domain wall junction at the geometric centre or 'core' of the flux closure object could give insight into the energetics of dipole misalignment.…”