Propulsion dispersion mediated ordering transition in active particles

We show that dispersion in propulsion strength qualitatively alters collective behavior of active multi-particle systems interacting via short-range attractive potential, giving rise to novel ordered phases that combine spatial and orientational ordering. Considering a binary mixture of active Brownian particles with two distinct self-propulsion strengths, we find that, the interplay between interaction range, self-propulsion strengths and the relative numbers of the particles with different propulsion strengths can lead to three different phases, namely, a disordered one, and two ordered ones with partial and complete spatial and orientational ordering. The partially ordered phase is characterized by formation of a ring-like assembly of the slower particles while the faster particles diffuse randomly. Two concentric rings, comprising faster and slower particles, form in the fully ordered phase. Using the example of a truncated harmonic potential, we analytically characterize the phase boundaries and identify the associated order parameters. Our results demonstrate that propulsion dispersion provides a robust and novel route to collective ordering in attractive active matter.