Solid state physics - Phase separation scenario for manganese oxides and related materials

Recent computational studies of models for manganese oxides have revealed a rich phase diagram, which was not anticipated in early calculations in thi s context performed in the 1950s and 1960s. In particular, the transition b etween the antiferromagnetic insulator state of the hole-undoped limit and the ferromagnetic metal at finite hole density was found to occur through a mixed-phase process. When extended Coulomb interactions are included, a mi croscopically charged inhomogeneous state should be stabilized. These phase separation tendencies, also present at low electronic densities, influence the properties of the ferromagnetic region by increasing charge fluctuatio ns. Experimental data reviewed here by applying several techniques for mang anites and other materials are consistent with this scenario. Similarities with results previously discussed in the context of cuprates are clear from this analysis, although the phase segration tendencies in manganites appea r stronger.