Magnetoresistance Behavior of (La_(2/3)Ca_(1/3))(Mn_((3-x)/3)Fe_(x/3))O_3 System

The temperature dependence of electrical resistance and magnetoresistance as well as field dependence of magnetoresistance at fixed temperature of the (La2/3Ca1/3)((Mn(3-x)/3Fex/3)O3(x=0, 0.1, 0.2, 0.3) system were systematically measured. It was found that when x increases, both the peak of the electrical resistivity and the peak of magnetoresistance move to lower temperature. However the giant magnetoresistance(GMR)is increased and its cusp is broadened by Fe substitution.The authors suggested that the variation of the proportion of Fe3+ ions leads to the changes of the ratios of Mn3+ to Mn4+ and magnetic moments while external magnetic field modulstes the magnetic ordered structure,so affects the ferromagnetic double exchange effect of the Mn3+-O-Mn4+. Finally, such phenomenon changes the behavior of magnetoresistance.