We explore the phase behavior of a population of polar microswimmers with off-center interaction sites in a two-dimensional periodic domain. The system exhibits a sequence of collective transitions as noise is decreased and interaction strength is increased. At high noise levels, the microswimmers remain in an isotropic disordered state. As noise is reduced, the system undergoes a transition to a polar swarm with collective motion and fluid-like behavior. Further reduction in noise and enhancement of interaction strength lead to the emergence of a hexatic phase, characterized by local sixfold bond-orientational order without long-range translational order. Eventually, the system develops solid-like features with positional order and suppressed fluctuations. These results reveal a rich landscape of non-equilibrium phase transitions in active matter, driven by the interplay of noise, polarity, and interaction geometry. Our findings provide a framework for understanding the organization of active particles in dense regimes and designing responsive active materials. R. Zayed and A. Nourhani acknowledge support from the National Science Foundation CAREER award, grant number CBET-2238915.
