GIANT MAGNETORESISTANCE AND MICROSTRUCTURE OF CO-CU AND FECO-CU GRANULAR FILMS

Co-Cu and FeCo-Cu granular films were prepared by DC (or RF) magnetron sputtering and post-deposition annealing. The influence of annealing conditions (temperature, duration) on GMR has been investigated system atically. It is found that the cumulative isothermal annealing at an o ptimal temperature (moderately high) promotes the precipitation of mag netic grains but limits their excessive growth, and therefore, leads t o more homogenous and smaller particles, which is in favor of the GMR improvement. By a combined study of TEM, magnetization and GMR, it is believed that the GMR in these granular films mainly originates from t he spin-dependent scattering of conducting electrons in the surfaces b etween magnetic particles and Cu matrix; especially, the very fine par ticles with a diameter of a few nm may be most effective for spin-depe ndent scattering.