Two-dimensional magnetic colloids under shear

摘要: Complex rheological properties of soft disordered solids, such as colloidal gels or glasses, inspire a range novel applications. However, the microscopic mechanisms their response to mechanical loading are not well understood. Here, we elucidate some aspects these by studying versatile model system, i.e. two-dimensional superparamagnetic colloids in precessing magnetic field, whose structure can be tuned from hexagonal crystal gel network varying external field opening angle θ. We perform Langevin dynamics simulations subjecting structures constant shear rate and observe three qualitatively different types material response. In crystals (θ = 0°), at sufficiently low rate, plastic flow occurs via successive stress drops which releases due formation dislocation defects. The θ 48°, on contrary, bond rearrangement transient banding evolves into homogeneously stretched large strains. latter remains metastable after switching off shear. At 50°, makes system unstable against phase separation causes failure leading close packed clusters interconnected particle chains. microcopic level, our provide insight strain localization occur simple gel-like network. Furthermore, demonstrate that new generated application