Magnetotransport study of Fe-Cr-Fe sandwiches grown on ZnSe(100)

Abstract

Magnetoresistance measurements have been performed on a set of molecular-beam epitaxy-grown Fe-Cr-Fe sandwiches with different chromium thicknesses, 12 Å<tCr<28 Å. For 13 Å<tCr<24 Å, magnetization measurements show that the Fe moments are antialigned at zero field. For samples exhibiting zero-field antialignment, negative magnetoresistance steps are observed at applied fields where discontinuities occur in the magnetization curve. The size of the magnetoresistance steps increases with increasing antiferromagnetic coupling between the Fe layers. The magnetoresistance [ρ(H)−ρ(0)]/ρ(0) is approximately proportional to cos2(Δφ/2), where Δφ≡(φ1−φ2), and φ1(H) and φ2(H) are the angles that the individual moments of the two Fe films make with the in-plane easy 〈100〉 axis.