THE POWER-LAW MAGNETIC-FIELD-DEPENDENCE OF THE GIANT MAGNETORESISTANCE RATIO IN LA0.67CA0.33MNOZ THIN-FILM

The temperature- and magnetic-field-dependences of the resistance in g iant magnetoresistance (GMR) La0.67Ca0.33MnOZ (LCMO) thin films have b een studied. it is found that the magnetoresistance ratio (R(M) = (R(O ) - R(H))/R(O) x 100%) can be expressed as R(M) proportional to A(T)H- alpha near the ferromagnetic transition temperature when H < 3 T. The temperature-dependence of R(M) is determined by A(T) and the exponent alpha approximate to 0.7 below 60 K and alpha approximate to 1.2 above 80 K. Under certain conditions, this kind of power-law magnetic-field -dependence of R(M) in LCMO thin film is similar to that in metallic m agnetic multilayer or grain-type GMR thin films.