Hyperuniform structures formed by shearing colloidal suspensions*

Time-reversibility is an essential feature of viscous, creeping flow that is lost when rigid particles suspended in the liquid are forced to collide with each other. In periodically sheared suspensions this loss manifests as a dynamical phase transition between reversible and chaotic particle trajectories characterized by a critical strain amplitude. Repulsive, non-hydrodynamic interactions between colliding particle surfaces have been proposed as the likely source of this broken symmetry, and a toy model that emphasizes particle collisions, called Random Organization¹, qualitatively reproduces the dynamical features of this transition. This model also displays a concomitant structural reorganization characterized by vanishingly small density fluctuations on long length-scales, called hyperuniformity, at criticality². Here we show that the particles in periodically sheared suspensions organize into structures with anisotropic short-range order but isotropic, long-range hyperuniform order when oscillatory shear amplitudes approach the critical strain amplitude.

1. Corte, Laurent, et al. Nature Physics (2008)
2. Hexner, Daniel, and Dov Levine. PRL (2015)