Active matter systems can exhibit coexisting patterns of competing symmetries

Active matter systems have the ability to produce a far greater variety of ordered patterns than conventional thermal equilibrium systems. In particular, transitions between disordered phases and either polar or nematically ordered phases have been predicted and observed in two-dimensional active systems. However, coexistence between phases of different types of order has not been reported. Here, we demonstrate the emergence of dynamic coexistence of ordered states exhibiting nematic and polar symmetry, both in large scale agent-based simulations as well as experimentally in an actomyosin motility assay that consists of actin filaments propelled by immobilized molecular motors.
We introduce a new type of active matter simulation that models extended, soft and semiflexible filaments which interact through a realistic contact interaction.
By combining simulation and experimental results, we identify sufficiently weak interactions of mixed alignment symmetry as an essential prerequisite for coexistence.
Thus, the symmetry of the macroscopic order itself becomes an emergent property of the active system.