Influence of ion irradiation on the magnetic properties of Fe/Cr multilayers

The influence of Ar-ion irradiation on the microstructure and magnetic properties of Fe/Cr multilayers is studied. An increase in the interface roughness of Fe/Cr multilayers, caused by irradiation with 200 keV Ar ions whose dose exceeds 5 x 10(12) Ar/cm(2), is clearly seen by conversion electron Mossbauer spectroscopy (CEMS). This modification of the microstructure induces distinct changes in the magnetization reversal (an increase in remanence magnetization and a decrease in saturation field), and greatly reduces the giant magnetoresistance (GMR) effect. on increasing the irradiation dose, An enhanced immunity of the GMR. effect to the ion irradiation on increasing the thickness of Cr layers. as well as correlation between the changes of GMR, and the antiferromagnetically coupled fraction, suggests that the main effect responsible for the decrease in GMR. is the formation of pinholes. The temperature dependence of remanence magnetization confirms increases in pinhole density and size during implantation. However, for doses exceeding 2 x 10(13) Ar/cm(2), volume intermixing seems to be a dominant mechanism responsible for the further degradation of GMR and the antiferromagnetic interlayer exchange coupling.