Giant magnetoresistance in La1−xSrxMnOz films near room temperature

Abstract

We report the observation of giant magnetoresistance near room temperature in ferromagnetic films of La_1−xSr_xMnO_z for 0.16≤x≤0.33. For B=5 T, the maximum magnetoresistance ratio [R(0)−R(B)]/R(0) of an annealed film is 60% at 260 K for x=0.2, and 35% at 330 K for x=0.33. Annealed films have higher Curie temperature (T_c), a larger saturation moment and a larger magnetoresistance effect near T_c than do as‐grown films. The temperature dependence of resistivity for all the samples investigated is unusual, activated above T_c and metallic below T_c. This and the giant magnetoresistance are possibly explained by scattering from magnetic polarons which dominate the transport near T_c.