Negative Magnetoresistance Effect in La-Pb-Mn-O Bulk Manganese Oxides

The structure. magnetic and magnetotransport properties of La_1-xPb_xMnO bulk manganese oxides prepared by the standard ceramic techniques were investigated by XRD. VSM, ESM and MR measurements. The sintering condition and the hole doped concentration x have a strong influence on the magnetic properties and magnetoresistance effect. The maximum MR, 20% at room temperature under a field of 2T, was obtained for x= 0.4 and the sintered temperature T_s = 1260°C. The correlation among the structure, magnetic and MR is discussed.