Magnetization reversal and magnetic interactions in patterned spin valve structures

We have investigated the magnetization reversal and the magnetic anisotropy of epitaxial Co(112-bar0) and Fe(001) films and compared them with epitaxial Co(112-bar0)/Cr(001)/Fe(001) trilayers with spin valve characteristics. Furthermore, by e-beam lithography we have cut the single layers and the trilayers into the shape of wires to study the effect of the shape anisotropy and the dipolar interaction between the wires on their switching characteristics. We found that patterning very much affects the magnetization reversal of the single films by introducing an additional anisotropy term. Dipolar interaction between the different wires may exist but is less obvious. However, the remagnetization process of the patterned trilayers resembles more those of the continuous single films than a combination of the Co and Fe wires. We argue that this is due to a weak but remaining interlayer exchange coupling between Co and Fe, mediated by the intervening Cr layer.