Defect binding-unbinding transition in active nematic membranes

Fuente: arXiv
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Main Authors: Hirota, Yuki, Uchida, Nariya
Format: Preprint
Published: 2026
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author Hirota, Yuki
Uchida, Nariya
author_facet Hirota, Yuki
Uchida, Nariya
contents We investigate the dynamics of active nematic liquid crystals on deformable membranes, focusing on the interplay between active stress and anisotropic curvature coupling. Using a minimal model, we simulate the coupled evolution of the nematic order parameter and membrane height. We demonstrate a continuous transition from a curvature-dominated regime, where topological defects are trapped by local deformation, to an activity-dominated regime exhibiting active turbulence. A scaling analysis reveals that the critical activity threshold $ζ_c$ scales as $α^2/κ$, where $α$ and $κ$ are the coupling constant and bending stiffness, respectively; this relationship is confirmed by our numerical results. Furthermore, we find that significant correlations between the orientational pattern and membrane geometry persist even in the turbulent regime. Specifically, we identify that "walls" in the director field induce characteristic wave-like curvature profiles, providing a mechanism for dynamic coupling between order and shape. These results offer a physical framework for understanding defect-mediated deformation in nonequilibrium biological membranes.
format Preprint
id arxiv_https___arxiv_org_abs_2602_10521
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Defect binding-unbinding transition in active nematic membranes
Hirota, Yuki
Uchida, Nariya
Soft Condensed Matter
We investigate the dynamics of active nematic liquid crystals on deformable membranes, focusing on the interplay between active stress and anisotropic curvature coupling. Using a minimal model, we simulate the coupled evolution of the nematic order parameter and membrane height. We demonstrate a continuous transition from a curvature-dominated regime, where topological defects are trapped by local deformation, to an activity-dominated regime exhibiting active turbulence. A scaling analysis reveals that the critical activity threshold $ζ_c$ scales as $α^2/κ$, where $α$ and $κ$ are the coupling constant and bending stiffness, respectively; this relationship is confirmed by our numerical results. Furthermore, we find that significant correlations between the orientational pattern and membrane geometry persist even in the turbulent regime. Specifically, we identify that "walls" in the director field induce characteristic wave-like curvature profiles, providing a mechanism for dynamic coupling between order and shape. These results offer a physical framework for understanding defect-mediated deformation in nonequilibrium biological membranes.
title Defect binding-unbinding transition in active nematic membranes
topic Soft Condensed Matter
url https://arxiv.org/abs/2602.10521