Phase separation tendencies in manganites as a possible explanation of theCMR effect

This paper is a brief review of the present status of the computational stu dies of models for manganites that recently reported the existence of phase separation at low-temperatures (S. Yunoki et al., Phys. Rev. Lett. 80, 845 (1998); 81, 5612 (1998) and references therein). Results for both the one- orbital and two-orbital models, the latter with Jahn-Teller phonons, are di scussed. The spin-canted phase widely believed until recently to exist at l ow hole-density is not stable. The tendencies to charge clustering suggest that local mean-field approaches may not be suitable for the study of model s for manganites, especially at finite temperatures where the phase separat ion tendencies will be dynamic rather than static. A large list of experime ntal results are compatible with the existence of charge-inhomogeneities in the manganites, which may be an important ingredient for the explanation o f the CMR effect in these compounds. (C) 1999 Elsevier Science S.A. All rig hts reserved.