Coupling of odd force and odd mobility induces nonmonotonic diffusion in a chiral Kob–Andersen mixture

Odd interaction forces break time-reversal and parity symmetries, driving systems out of equilibrium and enabling unconventional transport. The combined effect of odd interactions and odd mobility on chiral particle diffusion remains unexplored. Here, we investigate diffusion in a two-dimensional Kob–Andersen mixture driven by odd forces and odd mobility, where the latter modifies the particle velocity response. We find that transverse forces and odd mobility individually promote diffusion, but their coupling suppresses it by inducing localized vortex-like motion. Particle number density plays a dual role: collisions can suppress diffusion, yet at higher densities they break vortex localization; additionally, reduced interparticle distance enhances transverse transport. Interestingly, the coupling is fragile—at higher densities, frequent collisions dismantle its suppression and strongly boost diffusion. Consequently, diffusion exhibits complex, nonmonotonic behavior. This nonmonotonicity gives rise to optimal transport at high densities, with increasing transverse forces and odd mobility further enhancing it.