Micro-excitations in Coulomb liquids

Abstract

In a two-dimensional liquid melted from a triangular lattice, the accumulation of constructive perturbation from thermal noise and other external slow drive can cause stick–slip type particle hopping over the caging barrier formed by the surrounding particles, which in turn distort the order lattice structure and generate topological defects. Through the strong mutual coupling, these nonlinear threshold-type micro-excitations of fast particles and topological defects usually occur in the form of avalanche type clusters involving a small number of sites. The dusty plasma liquid formed by suspending negatively charged micrometre sized particles in a low pressure discharge background turns out to be a good candidate to study the above spatio-temporal dynamical behaviours at the kinetic level through direct optical video microscopy. In this paper, we review our recent studies on this issue and compare the generic behaviours with other nonlinear coupled complex system excited by noise and other slow drives.