Theory of CPP magnetoresistance in spring ferromagnets

Magnetoresistance (MR) for currents perpendicular to planes (CPP) is calculated for spring ferromagnets in which an artificial domain wall is formed by external magnetic fields. We consider two contributions to the MR: one is caused by a twisting of the magnetization and the other is due to a mismatch of the electronic structure at interfaces. We show that the resulting MR may show a non-monotonic dependence on the width of the domain walls and can be either positive or negative according to the magnitude of these two contributions.