Self-organized and driven phase synchronization in coupled map scale free networks

As a model of evolving networks, we study coupled logistic maps on scale free networks. For small coupling strengths nodes show turbulent behavior but form phase synchronized clusters as coupling increases. We identify two different ways of cluster formation. For small coupling strengths we get {\it self-organized clusters} which have mostly intra-cluster couplings and for large coupling strengths there is a crossover and reorganization to {\it driven clusters} which have mostly inter-cluster couplings. In the novel driven synchronization the nodes of one cluster are driven by those of the others.