Appeal No. 95-5142
Application 08/078,917
exchange layer can be used adjacent to any exposed soft
magnetic layer regardless of that latter's function. Indeed,
Hempstead specifically distinguishes his invention in this
respect from Bajourek et al. U.S. Patent 3,840,898, which,
like the claimed invention, employs an exchange layer adjacent
to a soft magnetic biasing layer that is separated from a soft
magnetoresistive (MR) layer by a nonmagnetic layer (Hempstead
at col. 5, lines 10-35):5
Bajourek et al. . . . teach the use of exchange coupling
to produce permanent magnetic bias layers for an MR
stripe. They teach the use of exchange coupling between
an antiferromagnetic layer such as "Fe O and a soft
2 3
magnetic material such as 80:20 NiFe to produce a
permanent magnetic film which is then used to bias a
second soft magnetic film (the MR stripe) by
magnetostatic interaction between the two magnetic films
and/or by exchange coupling between the two magnetic
films through an insulating layer, for example, via
pinholes in the insulating layer as described below.
Nowhere do they teach the deliberate exchange between an
antiferromagnetic film and an MR stripe itself [for]
maintaining the soft magnetic properties of the MR
stripe. This is because, in that patent as discussed
above, for all known processes the exchange coupling
between a soft magnetic film and an antiferromagnetic
film caused an increase in the coercivity of the soft
magnetic film making it useless as an MR stripe (which
requires low coercivity and high permeability) but making
5The examiner should consider whether the subject matter
of Appellant's claims is anticipated by or rendered obvious by
Bajourek et al.
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