150% magnetoresistance in sputtered Fe/Cr(100) superlattices

We report the epitaxial growth of Fe/Cr(100) superlattices onto MgO(100) single-crystal substrates by magnetron sputtering. Superlattices that are epitaxially oriented within 1° both in-plane and out-of-plane with the MgO substrate are achieved by initial growth of a Cr base layer at high temperature. Multiple superlattice diffraction peaks are observed in the low- and high-angle x-ray diffraction spectra. Three peaks are observed in the magnetoresistance associated with the oscillatory antiferromagnetic interlayer magnetic coupling as a function of Cr thickness. A maximum magnetoresistance of 150% at 4.2 K (28% at room temperature) is observed for a Cr(100 Å)/[Fe(14 Å)/Cr(8 Å)]50 superlattice.