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arXiv · 2010.15106

Active-Particle Polarization Without Alignment Forces

Nicola Andreas Söker·Sven Auschra·Viktor Holubec·Klaus Kroy·Frank Cichos
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Abstract

Active-particle suspensions exhibit distinct polarization-density patterns in activity landscapes, even without anisotropic particle interactions. Such polarization without alignment forces is at work in motility-induced phase separation and betrays intrinsic microscopic activity to mesoscale observers. Using stable long-term confinement of a single hot microswimmer in a dedicated force-free particle trap, we examine the polarized interfacial layer at a motility step and confirm that it does not exert pressure onto the bulk. Our observations are quantitatively explained by an analytical theory that can also guide the analysis of more complex geometries and many-body effects.

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Nicola Andreas Söker, Sven Auschra, Viktor Holubec, Klaus Kroy, Frank Cichos. 2020-10-28. Active-Particle Polarization Without Alignment Forces. https://doi.org/10.1103/physrevlett.126.228001

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