Regensburg 2025 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 8: (Multi)ferroic States: From Fundamentals to Applications (III)
KFM 8.3: Vortrag
Dienstag, 18. März 2025, 10:15–10:30, H9
Vortex dynamics in incommensurate 2D and 3D bulk ferroics — •Aaron Merlin Müller1, Quintin Meier2, Andrés Cano2, Manfred Fiebig1, and Thomas Lottermoser1 — 1Department of Materials, ETH Zurich, 8093 Zurich, Switzerland — 2Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 25 Rue des Martyrs, 38042, Grenoble, France
We reveal that in 3D ferroic systems with competing incommensurate stripe phases of ferroic order and topological defects in the form of vortex lines, these vortex lines exhibit fundamentally different dynamics compared to their 2D counterparts. We show that loops of vortex lines can exhibit long relaxation times resulting from their positioning at saddle points in the energy landscape. Using phase-field simulations and analytical approaches, we demonstrate that the distinctive relaxation behavior in 3D systems arises from the interplay between dimensionality and the energy landscape of incommensurate stripe phases. Many ferroically ordered materials, such as hexagonal manganites and planar spin systems, feature periodic order parameters that support such competing orders. Hence, we employ a general model of two-component ferroic order whose findings generalize to all ferroic systems that exhibit vortices and incommensurate stripe phases. We analyze the dynamics of topological defects during the transition from inhomogeneous order without stripes to an incommensurate stripe phase in both 2D and 3D systems. We conclude by discussing the critical role of dimensionality in shaping the system’s energy landscape and broader implications for ferroic systems.
Keywords: XY Model; Hexagonal Manganites; Phase-Field Simulations; Time-dependent Ginzburg-Landau