Browse Prior Art Database

Spin Valve Read Head with Fe/A1203/Fe/NiFe Tunneling Junction

IP.com Disclosure Number: IPCOM000118618D
Original Publication Date: 1997-Apr-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Gill, HS: AUTHOR

Abstract

Spin polarized tunneling in ferromagnet/insulator/ferromagnet junctions has been shown to provide large magnetoresistance coefficient (>15%). The largest magnetoresistance coefficient is observed with Fe/A1203/Fe junctions. Spins of one of the "Fe" layers can be pinned by an antiferromagnet and other "Fe" layer is left free to respond to magnetic field to detect resistance change. However, "Fe" is not a suitable candidate for the free layer due to its high coercivity.

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Spin Valve Read Head with Fe/A1203/Fe/NiFe Tunneling Junction

      Spin polarized tunneling in ferromagnet/insulator/ferromagnet
junctions has been shown to provide large magnetoresistance
coefficient (>15%).  The largest magnetoresistance coefficient is
observed with Fe/A1203/Fe junctions.  Spins of one of the "Fe" layers
can be pinned by  an antiferromagnet and other "Fe" layer is left
free to respond to magnetic field to detect resistance change.
However, "Fe" is not a suitable candidate for the free layer due to
its high coercivity.

      Fe/A1203/Fe/NiFe type junction is proposed to obtain large
magnetoresistance coefficient together with soft magnetic properties
for the free layer for the spin valve head application.  The "Fe"
layer being near the junction maintains the high magnetoresistance
coefficient and magnetically soft NiFe which is exchange coupled to
the "Fe" provides magnetically soft free layer for the head.  The use
of this composite free layer concept allows several other material
systems, such as, half metallic material systems like Fe304 near the
junction to achieve high magnetoresistance coefficient due to their
high spin polarization.

      One embodiment of this invention is shown in the Figure.  The
sense current is allowed to flow perpendicular to the junction, known
as CPP configuration.  The ferromagnetic shields here also serve as
current carrying leads for the head.  This structure, therefore,
eliminates the gap insulatio...