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/M_{s}, a correlation not predicted by earlier
models of Fe-Cr magnetotransport.[3,6] A relationship between
the magnetoresistance and J/M_{s} is particularly
interesting in light of the fact that the interlayer coupling
parameter J is not a monotonic function of
t_{Cr}.[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/M_{s} could therefore have been anticipated using
Eqns. 1 and 2, which imply that the saturation field scales
with J/M_{s}.[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.

Wed Oct 11 09:49:01 PDT 1995