THEORY OF MANGANITES

摘要

The colossal magneto resistance observed in manganites has recently attracted considerable attention. Important advances in the understanding of the properties of these materials have been achieved by applying newly developed numerical techniques to the study of model Hamil-tonians proposed decades ago. The numerical discovery of electronic and structural phase separation, confirmed by experimental results, has been of particular relevance. The implicances of this phenomenon to the present understanding of the physics of manganites is discussed. Estimations of the resistivity in the mixed phase regime allows us to conclude that the intrinsic inhomogeneities of the Mn-oxides are crucial to understand their curious magneto transport behavior. The general aspects of the influence of quenched disorder on the competition between ordered states separated by a first-order transition are investigated and a new scale T~* for cluster formation is predicted.