Low field magnetoresistance in La0.67Sr0.33-x□xMnO3 perovskite system

We have studied magnetization, resistivity and magnetoresistance in polycrystalline La(0.67)Sr(0.33-x)rectangle(x)MnO(3) samples where 0 less than or equal to x less than or equal to 0.33. With varying x, powder X-ray diffraction patterns could be indexed in a rhombohedral and an orthorhombic perovskite structure. As the A-sits vacancy content increases, the resistivity of samples increases and the magnetic transition temperature shifts to lower temperature. The field dependence of magnetoresistance shows the presence of two distinct regimes. At low temperature the magnetoresistance was observed to be strongly dependent on the magnetization reaching a 17% variation of the resistivity in a low field of 2 kOe.