Regensburg 2022 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 19: Ferroics – Domains and Domain Walls 2

KFM 19.1: Vortrag

Mittwoch, 7. September 2022, 15:00–15:20, H7

Phase Field Simulations of the Dipolar Interaction in Hexagonal Manganites — •Aaron Merlin Müller, Amadé Bortis, Manfred Fiebig, and Thomas Lottermoser — Department of Materials, ETH Zurich, 8093 Zurich, Switzerland

We introduce a phase-field method that allows simulation of dipolar interaction in thin-film hexagonal manganites and investigate its effect on the unconventional ferroelectric vortex domain pattern of the material. Dipolar interactions are assumed to have negligible influence because of the improper nature of the ferroelectric order. Hence, dipolar interactions are commonly neglected when modeling such systems. Efficiently incorporating dipolar interactions of out-of-plane-oriented dipoles in phase-field methods is challenging as they represent a nonlocal Coulomb contribution to the free energy. In addition, the Coulomb interaction of a polarization field diverges at zero distance, unlike for atomistic dipole models. In our work, we show that including the dipolar interaction in the phase-field method results in more regular shaped domains in comparison to simulations that ignore the dipolar interaction, with lower variance in domain size. The ferroelectric domains of our revised approach resemble the experimentally observed patterns more closely. Hence, our work gives insights on the often neglected effects of dipolar interaction and the resulting depolarizing field on ferroelectric domains in an important class of improper ferroelectric materials.