Dt. Pierce et al., Effect of roughness, frustration, and antiferromagnetic order on magnetic coupling of Fe/Cr multilayers, J MAGN MAGN, 200(1-3), 1999, pp. 290-321
The interplay between interfacial disorder and the antiferromagnetic order
in Cr lends to complex behavior in Fe/Cr multilayers. Measurements of inter
layer coupling are discussed for samples with different amounts of disorder
ranging from optimally fabricated trilayers of Fe/Tr/Fe on Fe(0 0 1) whisk
ers, to trilayers with increasing degrees of interfacial roughness, and fin
ally to superlattices of Fe/Cr. The coupling of ferromagnets through noble-
metal spacer layers can be described by a model that consists of bilinear c
oupling averaged over thickness fluctuations and extrinsic biquadratic coup
ling induced by the thickness fluctuations. This, the conventional model, a
lso describes much of the behavior observed for Fe/Cr multilayers. However,
in this case, the antiferromagnetism in Cr lends to results not explained
by the conventional model. For nearly ideal interfaces, the Fe-Cr coupling
can induce order in Cr, modifying the temperature dependence of the interla
yer coupling. In addition, interfacial disorder can frustrate the antiferro
magnetic order in the Cr, leading to a variety of ordered states which have
been observed by neutron scattering. Each of these ordered states, in turn
modifies the interlayer coupling in unexpected ways. The different ways in
which the systems minimize the frustration can explain the experimental re
sults. (C) 1999 Elsevier Science B.V. All rights reserved.