Giant magnetoresistance and remanence in granular CoCu codeposited films

We present experimental magnetoresistance, magnetization, and remanence data for CoCu granular films obtained by electron beam codeposition, subsequently submitted to a thermal treatment. The magnetization measurements show coexistence of superparamagnetic and ferromagnetic (or blocked superparamagnetic) Co grains. By modeling the experimental magnetization curves, the distribution function of the superparamagnetic particle size, the volume fraction of the blocked part of the Co particles, and their saturation magnetization are obtained. delta M plots are constructed using the remanence curves. A correlation between the changes of the delta M parameters and those of the giant magnetoresistance, caused by the annealing, is discussed. (C) 1998 American Institute of Physics. [S0021-8979(98)46811-7].