Alignment-mediated segregation in an active-passive mixture

We report segregation between the athermal active and passive particles mediated by the local alignment interaction in a confined space. The competition between the alignment interaction and self-propulsion force results in a transition between disordered and ordered phases. We show that as the coordination between the particles increases, they form an ordered mill, which helps the particles to aggregate into isotropic clusters. As a result, particles segregate into active core and passive shells. This segregation phenomenon is adversely affected by the packing fraction and the size dispersion between active and passive particles. We show that this adverse effect can be overcome by incorporating higher coordination in the system. We report that the monodispersed system is more desirable for segregation in a binary mixture than a bidispersed system, as the latter favors the mixed state.