Effect of sputtering pressure-induced roughness on the microstructure and the perpendicular giant magnetoresistance of Fe/Cr superlattices

We have studied the connection between structure and magnetism of Fe/Cr sup erlattices as a function of sputtering pressure. To measure the perpendicul ar giant magnetoresistance, we have fabricated microstructured Fe/Cr pillar s embedded in SiO2 and interconnected with Nb electrodes. Because of the un iform current distribution in the Nb electrodes and the minimization of the superlattice-electrode contact resistance, the method allows a simple and independent measurement of the perpendicular superlattice resistance and gi ant magnetoresistance. A detailed quantitative structural analysis by x-ray diffraction, transmission electron microscopy, and high spatial resolution electron-energy-loss spectroscopy imaging, was correlated with magnetizati on and anisotropic magnetotransport properties. Structural characterization of [Fe(3 nm)/Cr(1.3 nm)](20), superlattices indicate that the roughness in creases monotonically with pressure. The current perpendicular to the plane giant magnetoresistance was also found to increase with pressure. This is interpreted as arising from an enhanced spin-dependent scattering.