  Microcrystals deform very differently from their macroscopic counterparts,
displaying a size-dependent yield stress and intermittent plastic strain
bursts. Here we demonstrate that size effects and strain bursts may be just two
different signatures of fundamental collective phenomena that govern the
dynamics of dislocation systems on all scales. We confirm this conjecture by
demonstrating agreement between the results of 2D and 3D dislocation dynamics
simulations and experimental results on compressed micropillars. Our results
indicate that many peculiarities of small-sample plasticity may arise from the
finite-size scaling properties of collective dislocation dynamics, rather than
from changes in the physical mechanisms governing dislocation motion.
