The effect of interfacial regions on the giant magnetoresistance in as-grown and annealed Fe/Cr MLFs

The influence of microstructure, in particular at the Fe/Cr interfaces on the giant magnetoresistance of both as-grown and annealed Fe/Cr multilayer films (MLFs) has been studied. The giant magnetoresistance varies with the spin-dependent resistivity, but the spin-independent resistivity was found to have a much greater effect on the magnitude of the giant magnetoresistance. A simple model was devised to determine the thickness t_mixed of the interfacial region across which the composition changed from pure Fe to pure Cr. The morphology of the interfaces was found to have a large influence on the magnitude of the giant magnetoresistance, and for a very diffused interface i.e. a large t_mixed, the giant magnetoresistance effect was suppressed. The optimum annealing condition was at a temperature of 300°C for 1 h, with changes in giant magnetoresistance being largely due to a decrease in the spin-independent resistivity upon annealing.