Structural and magnetic properties of Al doped Co-Ag granular films:: temperature dependence of magnetoresistance

The correlation between the structure, the magnetic and magnetotransport properties of sputter-deposited (Co90Al10)(x)Ag100-x granular films (19 less than or equal to x less than or equal to 45) are investigated. For an (Co90Al10) content of about 28% the magneto resistance (MR) ratio of the films reach its highest value of 6%. Al doping reduces the MR ratio in CoAg films, however, leads to a almost constant MR ratio against post annealing up to 773 K in (Co90Al10)(28)Ag-72 granular films, although the film structure is affected by annealing, respectively. According to magnetization measurements, superparamagnetic cobalt grains in the as-deposited (Co90Al10)(28)Ag-72 sample show after annealing up to 773 K both superparamagnetic and ferromagnetic behaviour. Annealing at 823 K causes a domain formation of large ferromagnetic grains with strong correlation. (C) 2004 Elsevier B.V. All rights reserved.