Shape-specific fluctuations of an active colloidal interface.

Active interface; C-shaped; Colloidal interfaces; Finite curvature; Interface heights; Parameter spaces; Roughness exponent; Self-propulsion; Steady state; Translational coupling; Physics and Astronomy (all); Physical and Theoretical Chemistry; Physics - Soft Condensed Matter; Physics - Statistical Mechanics

Abstract :

[en] Motivated by a recently synthesizable class of active interfaces formed by linked self-propelled colloids, we investigate the dynamics and fluctuations of a phoretically (chemically) interacting active interface with roto-translational coupling. We enumerate all steady-state shapes of the interface across parameter space and identify a regime where the interface acquires a finite curvature, leading to a characteristic "C-shaped" topology, along with persistent self-propulsion. In this phase, the interface height fluctuations obey Family-Vicsek scaling but with novel exponents: a dynamic exponent zh ≈ 0.5, a roughness exponent αh ≈ 0.9, and a super-ballistic growth exponent βh ≈ 1.7. In contrast, the orientational fluctuations of the colloidal monomers exhibit a negative roughness exponent, reflecting a surprising smoothness law, where steady-state fluctuations diminish with increasing system size. Together, these findings point toward a unique non-equilibrium universality class associated with self-propelled interfaces of non-standard shape.

Disciplines :

Physics

Author, co-author :

Subramaniam, Arvin Gopal ; Department of Physics, Indian Institute of Technology Madras, Chennai, India ; Center for Soft and Biological Matter, IIT Madras, Chennai, India

BANERJEE, Tirthankar ; University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Physics and Materials Science (DPHYMS)

Singh, Rajesh ; Department of Physics, Indian Institute of Technology Madras, Chennai, India ; Center for Soft and Biological Matter, IIT Madras, Chennai, India

External co-authors :

yes

Language :

English

Title :

Shape-specific fluctuations of an active colloidal interface.

Publication date :

21 January 2026

Journal title :

Journal of Chemical Physics

ISSN :

0021-9606

eISSN :

1089-7690

Publisher :

American Institute of Physics, United States

Volume :

164

Issue :

Peer reviewed :

Peer Reviewed verified by ORBi

Additional URL :

https://pubs.aip.org/aip/jcp/article-pdf/doi/10.1063/5.0301699/20876396/034901_1_5.0301699.pdf

Funders :

Luxembourg National Research Fund
DIA Fellowship, Govt of India

Funding text :

We thank Professors M. E. Cates and M. Muthukumar for useful discussions. We also thank the anonymous referee for their feedback and suggestions, which led to an improvement in the presentation of our results. A.G.S. acknowledges funding from the DIA Fellowship from the Government of India. T.B. was supported through the Luxembourg National Research Fund (FNR), Grant Reference No. C22/MS/17186249.

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