Phase separation scenario for manganese oxides

Recent computational studies of models for manganese oxides have revealed a rich phase diagram, not anticipated in early calculations in this context, In particular, the transition between the antiferromagnetic insulator of t he hole-undoped limit and the ferromagnetic metal at finite hole-density wa s found to occur through a mixed-phase process. Experimental data for manga nites and other materials are consistent with this scenario. More recently, the influence of disorder on first-order transitions present in non-disord ered manganite models has been shown to lead to giant cluster coexistence, as reported in several experiments. Inhomogeneities clearly regulate the ph ysics of manganites. Here, a simple model is presented for the calculation of resistivities in the mixed-phase regime. The results are in excellent qu alitative agreement with experiments. (C) 2001 Elsevier Science B.V. All ri ghts reserved.