Phase Separation in Models for Manganites: Theoretical Aspects and Comparison with Experiments

Summarizing, a comprehensive computational study of models for manganites have found that the expected double-exchange induced strong tendencies to ferromagnetic correlations at low temperatures are in competition with a regime of “phase separation”. This regime was identified in all dimensions of interest, using one and two orbitals (the latter with Jahn-Teller phonons), and both with classical and quantum localized t2g spins. It also appears in the presence of on-site Coulomb interactions. This robustness of our results suggests that phase separation may also be present in real manganites. In the previous section experimental literature that have reported some form of charge in-homogeneity in the context of the manganites has been briefly reviewed. It is concluded that theory and experiments seem to be in qualitative agreement and phase separation tendencies (which may correspond to the formation of magnetic droplets or even stripes once Coulomb interactions beyond the on-site term are included in the analysis) should be taken seriously. They may even be responsible for the phenomenon of Colossal Magnetoresistance that motivated the current enormous interest in the study of manganites in the first place!.