Magnetoresistance in epitaxial FeCr(001) superlattices grown on MgO(001) and sapphire(1102) substrates

To clarify the effect of the substrate on the giant magnetoresistance of epitaxial FeCr(001) superlattices, Cr-thickness dependence of both magnetoresistance (MR) and magnetization are studied using the same superlattice structure grown on different substrates, MgO(001) or Al2O3(1102). With varying thickness of Cr layer, the MR ratio undergoes an oscillatory behavior. At the first peak (∼ 1 nm Cr), the superlattice on sapphire shows a larger MR ratio and a larger saturation field than that on MgO. At the second peak (∼ 1.7 nm Cr), however, a larger MR ratio is observed for the superlattice on MgO.