AVALANCHES IN THE BEAN CRITICAL-STATE - A CHARACTERISTIC OF THE RANDOM PINNING POTENTIAL

We report on two-dimensional simulations of the avalanche response of vortices in the Bean critical state of type-II superconductors. Two di fferent kinds of repulsive-particle models are considered in order to make the findings generic. We use repulsive two-body potentials to rep resent the vortex-vortex interaction and an attractive two-body potent ial to represent the interaction between the static pinning wells and the vortices. We find that a collection of very short-ranged dense pin ning centres leads to a broad distribution of response avalanches, whe reas broader and less dense pinning centres produce a narrow distribut ion of responses.