Novel high-temperature ferroelectric domain morphology in PbTiO₃ ultrathin films

Abstract

Exotic domain morphologies in ferroic materials are an exciting avenue for the development of novel nanoelectronics. In this work we have used large scale molecular dynamics to construct a strain-temperature phase diagram of the domain morphology of PbTiO3 ultrathin films. Sampling a wide interval of strain values over a temperature range up to the Curie temperature Tc, we found that epitaxial strain induces the formation of a variety of closure-and in-plane domain morphologies. The local strain and ferroelectric-antiferrodistortive coupling at the film surface vary for the strain mediated transition sequence and this could offer a route for experimental observation of the morphologies. Remarkably, we identify a new nanobubble domain morphology that is stable in the high-temperature regime for compressively strained PbTiO3. We demonstrate that the formation mechanism of the nanobubble domains morphology is related to the wandering of flux closure domain walls, which we characterise using the hypertoroidal moment. These results provide insight into the local behaviour and dynamics of ferroelectric domains in ultrathin films to open up potential applications for bubble domains in new technologies and pathways to control and exploit novel phenomena in dimensionally constrained materials.

Domain Wall Orientations in Ferroelectric Superlattices Probed with Synchrotron X-Ray Diffraction

“…The multicomponent nature of the order parameter in ferroelectrics also means that changes in the DW character (e.g. the effect of in-plane polarization components) 31,[36][37][38][39] and chirality are also likely to influence both the DW width 40 and preferred orientation; further experimental and theoretical work is needed to clarify this issue.…”

Polar Morphologies from First Principles: PbTiO3Films on SrTiO3Substrates and the p(2×Λ) Surface Reconstruction

“…[ 36,37 ] To overcome these limitations, some resort to alternative methods including phase fields, shell models, Monte Carlo, and second principles. [ 12,13,38–43 ] Whilst these approaches each have their merits, they cannot universally serve as a replacement for full DFT. Most of these methods implicitly accept that full DFT offers superior accuracy since they either are or can be parameterized by the theory.…”

Improving the Functional Control of Aged Ferroelectrics Using Insights from Atomistic Modeling

“…This is followed by an 8 ps production run over which statistics are collected (total of 12 ps per iteration). We calculate the local polarisation by considering conventional Ti-centred unit cells as implemented in references [24,25,28]. Further details are provided in the Supplementary Information.…”