Electron-doped manganese perovskites: The magnetic polaron state

Using the Lanczos method in linear chains we study the ground state of the double exchange model including an antiferromagnetic superexchange in the l ow concentration limit. We find that this ground state is always inhomogene ous, containing ferromagnetic polarons. The extension of the polaron spin d istortion, the dispersion relation and its trapping by impurities, are stud ied for different values of the superexchange interaction and magnetic fiel d. We also find repulsive polaron-polaron interaction.