Colloidal systems with competing interactions: from an arrested repulsive cluster phase to a gel

We report an extensive numerical study of a charged colloidal system with competing short-range depletion attraction and long-range electrostatic repulsion. By analyzing the cluster properties, we identify two distinct regions in the phase diagram: a state composed of stable finite-size clusters, whose relative interactions are dominated by long-range repulsion, and a percolating network. Both states are found to dynamically arrest at low temperatures, providing evidence of the existence of two distinct non-ergodic states in these systems: a Wigner glass of clusters and a gel.