Parallel and perpendicular transport in multilayered structures

The difference between parallel and perpendicular conductance in magnetic superlattices such as Fe/Cr are studied numerically with the Kubo formula and a recursion method. In the calculation, the multilayered structure of superlattices is taken into account through a periodic potential along the direction normal to the interfaces. It is shown that the magnetoresistance for the current parallel to the layers ${\mathit{MR}}_{\mathrm{\parallel }}$ is increased by the interface roughness and decreased by the bulk impurity scattering. Since the Brillouin zone is divided into a series of minizones due to the periodic potential, the magnetoresistance for the current perpendicular to the layers ${\mathit{MR}}_{\mathrm{\perp }}$ is determined by the miniband structure and becomes larger than ${\mathit{MR}}_{\mathrm{\parallel }}$.