Spontaneous crystallization of chiral active colloidal particles

The crystallization dynamics of chiral active colloids are explored numerically. It is found that chiral colloids with large angular velocity could be localized by self-trapping, which promotes the formation of hexagonal crystal structures. The competition between chirality and coupling strength leads to the transition between liquid and solid regimes. Comparing to the achiral particles, the transition points shift towards the weak coupling region greatly with the increasing degree of chirality. The hexagonal structure seems more tenacious and more difficult to melt. Therefore, the solid–liquid coexistence region shrinks in the phase diagram. In the low rotational speed region, active particles swap neighbors rapidly, the system becomes globally ordered but undergoes a nonnegligible diffusion, leading to the structural ordering occurrence before dynamical freezing.