Exploiting Disorder

Abstract

We are taught to understand solids by considering ideal crystals. This approach becomes untenable as the amount of disorder increases; for a glass with no well-defined long-range order, a crystal is an abysmal starting point for understanding the glass’s rigidity and excitations. Is there an alternative – the opposite of a crystal – where order, rather than disorder is the perturbation? Jamming is an alternate way of creating rigid solids that are qualitatively different from crystals. In a crystal with one atom per unit cell, all atoms produce the same response to external perturbations. Jammed materials are not similarly constrained and a new principle emerges: independence of bond-level response. Using networks where individual bonds can be successively removed, one can drive the system to different regimes of behavior. Consequently, one can exploit disorder to achieve unique, varied, textured and tunable response from auxetic to allosteric behavior.