Abstract
Studies of active matter, from molecular assemblies to animal groups, have revealed two broad classes of behaviour: a tendency to align yields orientational order and collective motion, whereas particle repulsion leads to self-trapping and motility-induced phase separation. Here we report a third class of behaviour: orientational interactions that produce active phase separation. Combining theory and experiments on self-propelled Janus colloids, we show that stronger repulsion on the rear than on the front of these particles produces non-reciprocal torques that reorient particle motion towards high-density regions. Particles thus self-propel towards crowded areas, which leads to phase separation. Clusters remain fluid and exhibit fast particle turnover, in contrast to the jammed clusters that typically arise from self-trapping, and interfaces are sufficiently wide that they span entire clusters. Overall, our work identifies a torque-based mechanism for phase separation in active fluids, and our theory predicts that these orientational interactions yield coexisting phases that lack internal orientational order.
| Original language | American English |
|---|---|
| Pages (from-to) | 961-967 |
| Number of pages | 7 |
| Journal | Nature Physics |
| Volume | 17 |
| Issue number | 8 |
| DOIs | |
| State | Published - Aug 2021 |
ASJC Scopus subject areas
- General Physics and Astronomy