Shifted hysteresis loops characteristic of the exchange-bias effect
between a ferromagnet (F) and an
antiferromagnet (AF) are demonstrated in "double-superlattice" structures.
Utilizing the
well-established oscillatory interlayer exchange coupling in Fe/Cr, we
have constructed
[Fe/Cr]AF/Cr/[Fe/Cr]F double superlattices where Fe/Cr superlattices with
appropriate Cr-spacer
thickness represent the F and the AF. The double superlattices are
(211)-oriented epitaxial films
sputter grown on single-crystal MgO(110) substrates. The AF/F interface is
coherent compared to
conventional exchange-bias interfaces consisting of dissimilar AF and F
phases. Magnetization
results show that AF/F exchange coupling affects the nucleation of reverse
magnetic domains, and
that the magnitude of the exchange-bias field is given directly by the
classic formula for collinear
spin structures. The collinear spin distribution is confirmed by polarized
neutron reflectivity.
©2000 The American Physical Society