Note that a completely quantitative treatment of the Fe-Cr-Fe magnetoresistance will require the formulation of a unified expression, Dr/r(theta, DeltaPhi), which incorporates both contributions to the magnetoresistance. This analysis is in progress. At present, the good agreement between the two curves in Fig. 4 is an indication that the antialignment-derived effects are dominant.
In order to look for a relationship between the magnitude of the magnetoresistance and the magnetic properties of the sandwiches, the magnitude of the transverse magnetoresistance was determined for 8 different antiferromagnetically coupled samples with varying Cr thicknesses. Figure 5 shows that the transverse magnetoresistance magnitude increases with increasing J/Ms, a correlation not predicted by earlier models of Fe-Cr magnetotransport.[3,6] A relationship between the magnetoresistance and J/Ms is particularly interesting in light of the fact that the interlayer coupling parameter J is not a monotonic function of tCr.[5,7]
The data of Ref. [3] show that in antiferromagnetically coupled Fe-Cr superlattices, as in the Fe-Cr sandwiches, [Dr/r]sat increases with increasing saturation field. The correlation of [Dr/r]sat with J/Ms could therefore have been anticipated using Eqns. 1 and 2, which imply that the saturation field scales with J/Ms.[5,7] Further progress should be possible in understanding the Fe-Cr system once this interlayer-coupling dependence can be incorporated into a microscopic model of transport. Such a model will have to be consistent with the existing theory,[6] which satisfactorily explains the dependence of the magnetoresistance on temperature and on the number of Fe/Cr interfaces.