Recent neutron experiments on CMR manganites have revealed anomalies in the spin excitation spectrum such as broadening, branching, and anticrossing with gap opening. Here we present our theoretical results on the spin excitation of the double-exchange model with quenched disorder. We will show that inhomogeneity due to disorder is a strong candidate for a comprehensive understanding of the anomalous features in experimental results. We will also discuss recent progress on the droplet-like clustered state at low doping
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