Giant Magnetoresistance from an Electron Waveguide Effect in Cobalt-Copper Multilayers

Calculations of the electrical conductivity and giant magnetoresistance of cobalt-copper multilayers show that these properties can be strongly affected by a waveguide effect. Majority electrons in cobalt have a lower Fermi momentum than in copper. This leads to total internal reflection of electrons whose momentum parallel to the interface exceeds a critical value. This waveguide effect will strongly influence the current distributions in the multilayer if the interfaces are sufficiently smooth, and it will contribute to the giant magnetoresistance if the scattering rates are significantly different in copper and cobalt.