Magnetoresistance in Magnetic Tunnel Junctions with Nonmagnetic Metallic Spacers and Cap Layers

In a free-electron approximation, transport properties of magnetic tunnel junctions with nonmagnetic metallic spacers and cap layers were studied. The magnetoresistance is oscillatory functions of the thicknesses of non-magnetic metallic spacers and ferromagnets, their period is determined by the Fermi surface properties of the metals, and magnetoresistances (up to about 10³%) much greater than those predicted by the Julliere's model are obtained. The results indicate that this structure has potential in designing spin-polarized tunneling devices.