Motility Induced Phase Separation and Frustration in Active Matter Swarmalators

We introduce a system of active matter swarmalators composed of elastically interacting run-and-tumble active disks with an internal phase ϕi. The disks experience an additional attractive or repulsive force with neighboring disks depending upon their relative difference in ϕi. In the absence of the internal phase, the system forms a Motility-Induced Phase Separated (MIPS) state, but when the swarmalator interactions are present, a wide variety of other active phases appear depending upon whether the interaction is attractive or repulsive and whether the particles act to synchronize or anti-synchronize their internal phase values. These include a gas-free gel regime, arrested clusters, a labyrinthine state, a regular MIPS state, a frustrated MIPS state for attractive anti-synchronization, and a superlattice MIPS state for attractive synchronization.