ICMCS Seminar - Reentrance in a Hamiltonian flocking model

Title: Reentrance in a Hamiltonian flocking model

Abstract: The clustering of self-motile and repulsive particles, so-called motility-induced phase separation (MIPS), is one of the clearest signatures of active physics. Typically, increasing the amplitude of self-motility increases the degree of clustering, however for high enough self-motility the homogeneous phase is reentered. Here, we report that such reentrance naturally emerges in an overdamped Hamiltonian model, with such a model recapitulating properties of (active) bird flocks, and exhibits clustering behaviour reminiscent of MIPS. We demonstrate the reentrance of the homogeneous phase and identify the underlying mechanism as a competition between the amplitude of a spin-velocity coupled drive and mobility-limited kinetic frustration. We reveal, both numerically and analytically, that strong spin-velocity coupling suppresses transverse diffusion, which causes a dimensional reduction for the particle dynamics, thereby leading the system into an arrest that closes the window for phase separation. Overall, our work offers a Hamiltonian bridge between reentrant physics across equilibrium and non-equilibrium materials.

Join Zoom Meeting
https://ed-ac-uk.zoom.us/j/81211470751

Meeting ID: 812 1147 0751
Passcode: ICMCS123