Increases in giant magnetoresistance by ion irradiation

We have studied the effect of 500-keV ${\mathrm{Xe}}^{+}$ irradiation on the structure, magnetotransport, and magnetic properties of sputtered Fe/Cr multilayers. Initially, with increasing dosage the giant magnetoresistance (GMR) increases with a concomitant increase in the interfacial roughness as indicated by changes in the low-angle x-ray-diffraction spectra. At doses higher than 1×${10}^{13}$ ions/${\mathrm{cm}}^2$, the value of the GMR progressively decreases, corresponding to progressively increasing regions of the film which are ferromagnetically coupled. The resulting structural disorder increases the overall electronic scattering rate and hence the electrical resistance at these higher doses. These results demonstrate that increased interfacial scattering enhances the GMR and thus plays an important role in the mechanism determining the GMR in Fe/Cr superlattices.