Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2005-01-25
2005-01-25
Renner, Craig A. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S324120, C365S158000, C365S171000
Reexamination Certificate
active
06847510
ABSTRACT:
A magnetic tunnel junction (MTJ) device usable as a magnetic memory cell or magnetoresistive sensor, such as a MTJ read head for magnetic recording, has the free ferromagnetic layer located on the bottom of the device, the bottom free layer being formed on a special underlayer. The MTJ read head may be a flux-guided head that uses the free layer as a flux guide for directing magnetic flux from the magnetic media to the sensing region of the MTJ. The special underlayer for the growth of the free layer is an alloy comprising Mn, one of Pt, Ni, Ir and Os, and an additive X selected from Ta, Al, Ti, Cu, Cr and V. Without the additive, the underlayer alloy is antiferromagnetic. The additive is present in an amount sufficient to render the alloy to have no magnetic ordering, i.e., it is neither antiferromagnetic nor ferromagnetic, but without substantially affecting the preferred crystalline texture and unit cell size so that the underlayer is well-suited as a growth-enhancing underlayer for the free layer.
REFERENCES:
patent: 5650958 (1997-07-01), Gallagher et al.
patent: 5898547 (1999-04-01), Fontana, Jr. et al.
patent: 5898548 (1999-04-01), Dill et al.
Childress Jeffrey R.
Fontana, Jr. Robert E.
Ho Kuok San
Tsang Ching Hwa
Berthold Thomas R.
Hitachi Global Storage Technologies - Netherlands B.V.
Renner Craig A.
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