Micro-Origin of Visco-Elasticity in Mesoscopic 2D Dusty Plasma Liquids

Summary form only given. When the confinement width goes down to the atomic scale, the thin liquid becomes partially solid-like and exhibits visco-elastic response to an external shear pulse. However, the small atomic scale makes the direct visualization for the micro-motion and structural rearrangement difficult. In this work, using a confined thin 2D dusty plasma liquid sheared by two periodically modulated counter parallel laser beams, we explore the physical origin of the viscous and elastic responses of the thin liquid. The percolation clusters of ordered triangular lattice domains are responsible for the elastic response. The structural rearrangement associated with the defect type clusters washes out the local structure memory under shear, and is responsible for the viscous plastic response.