  We study particle-scale motion in sheared highly polydisperse amorphous
materials, in which the largest particles are as much as ten times the size of
the smallest. We find strikingly different behavior from the more commonly
studied amorphous systems with low polydispersity. In particular, analysis of
the nonaffine motion of particles reveals qualitative differences between large
and small particles: the smaller particles have dramatically more nonaffine
motion, which is induced by the presence of the large particles. We
characterize the crossover in nonaffine motion from the low- to
high-polydispersity regime, and demonstrate a quantitative way to distinguish
between "large" and "small" particles in systems with broad distributions of
particle sizes.
