Nonreciprocal collective dynamics in a mixture of phoretic Janus colloids

Journal article

A multicomponent mixture of Janus colloids with distinct catalytic coats and phoretic mobilities is a promising theoretical system to explore the collective behavior arising from nonreciprocal interactions. An active colloid produces (or consumes) chemicals, self-propels, drifts along chemical gradients, and rotates its intrinsic polarity to align with a gradient. As a result the connection from microscopics to continuum theories through coarse-graining couples densities and polarization fields in unique ways. Focusing on a binary mixture, we show that these couplings render the unpatterned reference state unstable to small perturbations through a variety of instabilities including oscillatory ones which arise on crossing an exceptional point or through a Hopf bifurcation. For fast relaxation of the polar fields, they can be eliminated in favor of the density fields to obtain a microscopic realization of the Nonreciprocal Cahn–Hilliard model for two conserved species with two distinct sources of non-reciprocity, one in the interaction coefficient and the other in the interfacial tension. Our work establishes Janus colloids as a versatile model for a bottom-up approach to both scalar and polar active mixtures.

Authors: Tucci, G; Golestanian, R; Saha, S

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: IOP Publishing
• Journal: New Journal of Physics
• Volume: 26
• Issue: 7
• Article number: 073006
• Publication date: 2024-07-03
• Acceptance date: 2024-05-28
• DOI: 10.1088/1367-2630/ad50ff
• EISSN: 1367-2630
• Language: English
• Keywords: nonreciprocal; phoretic; collective; Janus; dynamics; mixtures