ABSTRACT
The colossal magnetoresistance (CMR) effect consists of an abrupt decrease in the resistance upon the imposition of magnetic field. In spite of experimentally determined, optimal from the point of view of CMR relationships between lanthanum and alkaline earth elements in manganites a rather large interest of the researchers is attracted to manganites with the substitution of lanthanum atoms for a half of bivalent elements. Magnetoresistance are devoted to the influence of rare earth elements introduced into the sublattice of lanthanum on the CMR effect. The use of only the size factors to account for such a behavior of magnetic susceptibility is evidently inadequate. The main role in the effect of colossal negative magnetoresistance seems to belong to a certain balance, competition between ferromagnetic and antiferromagnetic interactions rather than to ferromagnetic exchange between manganese atoms with different oxidation states.
