GIANT MAGNETORESISTANCE IN LA1-XSRXMNOZ FILMS NEAR ROOM-TEMPERATURE

We report the observation of giant magnetoresistance near room tempera ture in ferromagnetic films of La1-xSr(x)MnO(z) for 0.16 less-than-or- equal-to x less-than-or-equal-to 0.33. For B = 5 T, the maximum magnet oresistance 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 hig her Curie temperature (T(c)), a larger saturation moment and a larger magnetoresistance effect near T(c) than do as-grown films. The tempera ture dependence of resistivity for all the samples investigated is unu sual, 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). (C) 1994 American Ins titute of Physics.