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

We have studied magnetization, resistivity and magnetoresistance in polycry stalline 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 diffrac tion patterns could be indexed in a rhombohedral and an orthorhombic perovs kite 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 o f two distinct regimes. At low temperature the magnetoresistance was observ ed to be strongly dependent on the magnetization reaching a 17% variation o f the resistivity in a low field of 2 kOe.