Active Matter Commensuration and Frustration Effects on Periodic Substrates

TL;DR

This paper investigates how active particles interact with periodic obstacles, revealing unique commensuration and frustration effects, including crystalline states and transport anomalies, driven by activity and obstacle size variations.

Contribution

It introduces the concept of active matter commensuration effects on periodic substrates, highlighting phenomena absent in passive Brownian systems.

Findings

Active particles form crystalline states at specific obstacle sizes.

Peak six-fold ordering correlates with commensuration.

Mobility exhibits peaks and dips analogous to vortex and colloid systems.

Abstract

We show that self-driven particles coupled to a periodic obstacle array exhibit novel active matter commensuration effects that are absent in the Brownian limit. As the obstacle size is varied for sufficiently large activity, a series of commensuration effects appear in which the motility induced phase separation produces commensurate crystalline states, while for other obstacle sizes we find frustrated or amorphous states. The commensuration effects are associated with peaks in the amount of six-fold ordering and the maximum cluster size. When a drift force is added to the system, the mobility contains peaks and dips similar to those found in transport studies for commensuration effects in superconducting vortices and colloidal particles.