Band and percolation approaches to low temperature properties of manganites

Properties of the parent compound, LaMnO3 are greatly affected by strong Hu nd's coupling. Assuming the antiferromagnetic ordering (with a low Neel tem perature) along one of the cubic axes, this coupling would result in format ion of disconnected ferromagnetic layers. Furthermore, in the presence of t he cooperative Jahn-Teller effect the compound becomes a band insulator. At small doping (La1-xCaxMnO3, x much less than 1) the band insulator phase c oexists with the presence of localized holes. An insulator-ferromagnetic me tal transition occurs at the percolation point x(c) = 0.16.