Giant low-field magnetoresistance in polycrystalline La2/3Ca1/3Mn1-xCUxO3 sintered at 1100 °C

The La2/3Ca1/3Mn1-xCuxO3 (0 less than or equal to X < 6 %) samples were prepared by sol-gel method. Transport properties, conductive mechanism and low-field magnetoresistance (MR0) were investigated. It is found that conductive mechanism is described by Mott's variable-range hopping and the MR0 near the insulator-metal transition temperature (T-p) increases from 2 % to 80 % with x from 0 to 4 % for a low field of 0.3 T. The experiment also shows that the intergrain magnetoresistance. is largely improved. The results indicate that a proper amount of Cu doping can substantially improve magnetoresistance effects.