SKM 2023 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 1: Focus: Domains and Domainwalls in (Multi)Ferroics I

KFM 1.7: Vortrag

Montag, 27. März 2023, 11:35–11:55, POT 51

Effect of strain on the 3D domain structure of hexagonal manganites — Nelly Natsch, •Aaron Merlin Müller, Amadé Bortis, Manfred Fiebig, and Thomas Lottermoser — Department of Materials, ETH Zurich, 8093 Zurich, Switzerland

We simulate and visualize the three-dimensional domain structure of strained hexagonal manganites. Due to the improper nature of their ferroelectric order, hexagonal manganites exhibit unconventional vortex domain patterns. In 3D, these vortex domain patterns are characterized by vortex lines, which are 1D topological defects that form arbitrarily oriented loops in bulk materials. We show that when strain is applied in the ab-plane, the domains exhibit an additional stripe-like order that is oriented perpendicular to the ab-plane. In addition, we show that the strain also acts on the vortex lines, forcing them to form closed loops aligned in the same plane as the domain walls. In our simulations, we observe two types of loops: one type that expands and another type that contracts and collapses. We relate both the formation of the stripe-like domains and the evolution of the vortex-line loops to a force acting directly on the vortex lines which is induced by the applied strain. Our numerical investigation is performed with a phase-field model to simulate the domain structure in three dimensions using a Landau-free-energy expansion.