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 giant magnetoresistance (GMR) La0.67Ca0.33MnOZ (LCMO) thin films have been 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 magnetic multilayer or grain-type GMR thin films.