R. Seviour, S. Sanvito, C.J. Lambert, and J.H. Jefferson

We examine transport properties of a magnetic superlattice with current perpendicular to the planes. In the limit that the phase-breaking and spin flip scattering lengths are greater than the system size, a multiple-scattering approach is used to calculate the 4-probe conductance. We show that by tuning the strength of tunnelling barriers placed between the current and voltage probes magnetoresistance ratios of arbitrary strength and sign are achievable.