Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1998-12-28
2001-04-24
Heinz, A. J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S324110
Reexamination Certificate
active
06222707
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to magnetoresistive heads and more particularly to a method and system for providing a seed layer for the antiferromagnetic layer in bottom and dual spin valves.
BACKGROUND OF THE INVENTION
Currently, spin valves are conventionally used for the magnetoresistive (MR) element in MR heads. A spin valve includes two magnetic layers, a free layer and a pinned layer, a spacer layer, and a conventional antiferromagnetic (AFM) layer. The spin valve may also include a capping layer. The free layer and pinned layer are separated by the spacer layer. The magnetization of the pinned layer is typically fixed by exchange coupling to the conventional AFM layer.
A conventional MR head may include either a top spin valve or a bottom spin valve. A top spin valve is one in which the pinned layer and AFM layer are near the top of the spin valve, while the free layer is near the bottom of the spin valve, in proximity to the substrate. A bottom spin valve is one in which AFM layer and the pinned layer are near the bottom of the spin valve, while the free layer is near the top of the spin valve.
Typically, the conventional AFM layer in a top spin valve is formed of PtMn, PtPdMn, IrMn, NiMn, CrPtMn, RhMn, NiO, or NiCoO. If PtMn, PtPdMn, IrMn, NiMn, CrPtMn, or RhMn is used for the AFM layer in a bottom spin valve, the exchange coupling between the pinned layer and the conventional AFM layer is quite small. This reduces the magnetoresistance of the spin valve, lowering the signal provided by the MR head as well as the magnetic and thermal stability of the MR head. Consequently, the conventional AFM layer in a bottom spin valve is typically NiO or NiCoO. Bottom spin valves are more desirable than top spin valves for a variety of reasons. Accordingly, what is needed is a system and method for providing bottom and dual spin valves that can use an AFM layer other than NiO or CoO. Moreover, it would also be desirable to provide a bottom spin valve which uses a synthetic AFM layer. The present invention addresses such a need.
SUMMARY OF THE INVENTION
The present invention provides a method and system for providing a spin valve. The spin valve is formed on a substrate. In one aspect, the method and system comprise providing a seed layer including at least NiFe above the substrate and providing an antiferromagnetic layer on the seed layer. In this aspect, the method and system could comprise providing a NiFeCr seed layer or providing a multilayer of NiFe and Cu as the seed layer. The seed layer provides the desired texture for the antiferromagnetic layer. The method and system further comprise providing a pinned layer above the antiferromagnetic layer, the pinned layer being exchange coupled to the antiferromagnetic layer, providing a spacer layer above the pinned layer, and providing a free layer above the spacer layer. In a second aspect, the method and system comprise providing a seed layer including Cu instead of NiFe. In a third aspect, the method and system comprise providing a synthetic antiferromagnetic layer in lieu of the antiferromagnetic layer and the pinned layer. In this aspect, the seed layer provides the desired texture for the synthetic antiferromagnetic layer.
According to the system and method disclosed herein, the present invention can provide a bottom spin valve or a dual spin valve having improved exchange coupling between the antiferromagnetic layer and the pinned layer, thereby increasing the magnetoresistance and overall system performance.
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Anderson Geoffrey
Chen Wenjie
Hikami Fuminori
Huai Yiming
Zhu Ningjia
Heinz A. J.
Read-Rite Corporation
Sawyer Law Group LLP
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