Defect Dynamics in Amorphous Colloidal Monolayers under Shear

Abstract

Studying amorphous/disordered solids is challenging compared to their ordered counter parts, crystals. Lattice imperfections or defects in crystals are known to play a significant role in deformation, as the defects within crystals begin to move when an external load is applied, resulting in permanent deformation or plasticity. These defects are referred to as plasticity carriers. However, amorphous materials lack a reference lattice to identify defects. In this study, we use optical tweezers and dense colloidal suspensions to investigate the relationship between plastic activity and microscopic structure in amorphous substances. Shear fields in a colloidal monolayer are generated using a holographic optical trap with Laguerre Gaussian beam and a spatial light modulator. With this setup, we examine the relationships between defect dynamics and microstructure in a quasi-2D system of colloidal glasses, including the orientation of defects with respect to the shear direction. We have built the instrumentation of time-shared optical traps to investigate the effect of random pinning on phonon modes in colloidal crystals and glasses.