Antiskyrmions in ferroelectric barium titanate

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The present molecular dynamics computational study reveals that the bulk crystal of the archetypal ferroelectric perovskite (barium titanate) can host peculiar 2-3 nm wide standalone polar columns stable till temperatures of several tens of Kelvins. They are spontaneously surrounded by a unique noncollinear polarization pattern (see figure) that has never been described before. We explained how and why this pattern is formed and stabilized. Since its invariant skyrmion topological charge is an integer with a sign opposite to that of the usual skyrmions, they named this soliton as ferroelectric antiskyrmion. They clarify that formation of antiskyrmions consists in breakdown of high-curvature 180-degree ferroelectric walls into triplets of lower-energy 71-degree walls. It is explained that this process is favored by a fortunate combination of the moderate anisotropy of the anharmonic electric susceptibility and the pronounced anisotropy of the polarization correlations in barium titanate crystals. These findings represent a clear milestone in the studies of topological defects in ferroelectrics.

Antiskyrmion in BaTiO3
Description
Polarization pattern of the ferroelectric antiskyrmion in rhombohedral BaTiO3 obtained from atomistic shell-model based computational experiment.

Contact person: Jiří Hlinka, Department of Dielectrics