Defect motion and spin domain coarsening in buckled colloid simulations

When colloidal particles are vertically confined in a gap of between 1-2 particle diameters, they tightly pack into buckled crystals of particles in either "up" or "down" states, which are analogous to spin. When the gap is less than ~1.7 particle diameters, particles sit nearly on a triangular lattice, yielding geometric frustration for triangles of spins. Previous studies have focused on spin flips in this regime, but the role of underlying lattice defects on the coarsening of spin domains remains less explored. Our preliminary experimental results suggest that defect motion plays a dominant role in spin domain coarsening of unfrustrated configurations, while spin flips are more important in frustrated configurations. We investigate this via two simulation methods for buckled colloidal monolayers, one that allows particles to move in 3D, and a 2D simulation where opposite-spin particles interact with lower radius and there are no spin flips. By comparing these results to experiments in both unfrustrated and frustrated initial configurations, we determine the significance of lattice defect motion in each case and help disentangle lattice effects from spin effects.