Giant cluster coexistence in doped manganites and other compounds

Computational studies of models for manganese oxides show the generation of large coexisting metallic and insulating clusters with equal electronic de nsity, in agreement with the recently discovered micrometer-sized inhomogen eities in manganites. The clusters are induced by disorder on exchange and hopping amplitudes near first-order transitions of the nondisordered strong ly coupled system. The random-field Ising model illustrates the qualitative aspects of our results. Percolative characteristics are natural in this co ntext. The conclusions are general and apply to a variety of compounds.