Magnetoresistance in manganite/alumina nanocrystalline composites

Magnetotransport properties of manganite/insulator composites are studied i n this article. By merging the half metallic character of La2/3Ca1/3MnO3 an d the mixed composition with alumina grains dispersed in the structure we h ave been able to increase three times intergranular magnetoresistance aroun d the percolation threshold. The transport properties have been studied emp loying a theoretical model for ferromagnetic-insulator systems and a two ch annel equation in order to reproduce the behavior of resistivity in the who le temperature range. The percolation theory is introduced to try to unders tand and improve the fascinating properties of these mixed systems. (C) 200 1 American Institute of Physics.