Giant magnetoresistance in electro-deposited Co-Cu granular film

CoxCu100-x granular films have been successfully prepared by electrodeposit ion. The influences of deposition parameters and post-deposition annealing condition on giant magnetoresistance (GMR) have been studied in detail, usi ng transmission electron microscopy (TEM), vibrating sample magnetometer an d resistance measurements. It is found that, as for other methods, post-dep osition annealing is crucial for obtaining larger GMR value. Under the opti mum annealing condition, namely, annealing one hour at 695 K, GMR reaches a maximum value of -5% at room temperature, 1.3 T and -10% at 77 K, 0.9 T. A detailed TEM investigation shows that the grain size distribution follows a log-nonnal function. Using a recently developed model that takes explicit ly into account the magnetic moment distribution (therefore grain size dist ribution) and spin-dependent electron-impurity scattering within magnetic g rains and at the interface between grains and matrix for the granular films with superparamagnetic particles and considering the contribution from fer romagnetic grains, both experimental M-H and GMR-H curves have been well fi tted with this log-normal size distribution. Our results confirm this model and evidence that the spin-dependent scattering at the interface between m agnetic grains and non-magnetic matrix plays a dominant role for GMR, and g rain size distribution is crucial in explaining the experiment results on G MR.