High performance thin-film magnetic heads, such as giant
magnetoresistance [l] and spin-valve [2] (GMR) heads, are
being studied for magnetic recording. In addition to
providing a larger output than either an inductive or a
magnetoresistance (MR) head, the above GMR heads offer
the advantage of flux responsive characteristics. However,
the outputs are not large enough for future high density
recording, because their MR ratios are no more than - 10 %
(- 1%/0e). On the other hand, a large permeability change
ratio of several tens % (U 10%/Oe) has been used for other
field sensing techniques [3]-[5]. These techniques employ a
high frequency carrier, and the operations are flux
responsive. We have also reported that a UHF carrier type
head, which employs field dependent permeability at UHF,
exhibits a large voltage change ratio (corresponding to the
MR ratio) of - 60 % and a large full output of 20.5-127
mV p/pm for a static field [6]-[8], A broad bandwidth as
welf as a large output is required for high density heads.
This study describes the response of the head to a high
frequency signal field.