Dynamical arrest in colloidal monolayers induced by energy landscape

Using video microscopy, we experimentally investigate how a periodic potential landscape influences the dynamics of colloidal monolayers. The potential is generated by a layer of densely packed particles immobilized on the substrate, creating a spatially periodic gravitational field. In the absence of this external landscape, the monolayer behaves as a supercooled liquid: particles are temporarily confined by cages formed by neighboring particles but can escape over long time scales, allowing diffusive motion and structural rearrangement. As the strength of the imposed potential increases, the system undergoes a dynamical arrest. Particles become increasingly trapped in local minima of the external potential, leading to a dramatic slowdown of particle dynamics and a suppression of structural rearrangements. This strong spatial localization also hinders the cooperative motion of particles. As a result, dynamical heterogeneity is significantly reduced during the dynamical arrest. Our results show the critical role of the energy landscape in tuning colloidal dynamics and offer insight into dynamical arrest processes in complex environments.