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Thermally Stable Dual Spin Valves

IP.com Disclosure Number: IPCOM000014673D
Original Publication Date: 2000-Jun-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 27K

Publishing Venue

IBM

Abstract

Dual spin valve structures, whether in simple form or in AP-pinned form, provide higher GMR values. These structures however, require the antiferromagnetic layers to be at the bottom as well as at the top. It is generally observed that the GMR values are lower (15 to 40%) when metallic AF materials (IrMn, PtMn, etc.) are at the bottom. The NiO based spin valves, on the other hand, provide higher dR/R and better exchange when the NiO AF material is at the bottom. Therefore, combining the NiO based spin valve at the bottom with the metallic AF (IrMn, PtMn, NiMn, etc.) based spin valve on the top would provide better dual spin valve structures. One issue with the standard NiO spin valve is the thermal stability. The NiO/NiFe interface does not withstand high resetting temperatures (>240C) of metallic AF materials without significant loss of dR/R (>20%). One solution to this problem is to utilize a CoFe/NiFe/CoFe multilayered structure as the first pinned layer with the NiO AF material. This pinned layer structure provides high thermal stability with NiO/CoFe interface and lower coercivity with the addition of a NiFe layer. Therefore, a dual spin valve sensor with the following structure would provide high GMR values with good thermal stability. The structure is as follows: NiO/CoFe/NiFe/CoFe/Ru/CoFe/Cu/CoFe/NiFe/CoFe/Cu/CoFe/Ru/CoFe/Met. AF/Ta where metallic AF can be IrMn, PtMn, NiMn etc. 1

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Thermally Stable Dual Spin Valves

   Dual spin valve structures, whether in simple form or in AP-pinned form,
provide higher GMR values. These structures however, require the
antiferromagnetic layers to be at the bottom as well as at the top. It is
generally observed that the GMR values are lower (15 to 40%) when metallic AF
materials (IrMn, PtMn, etc.) are at the bottom. The NiO based spin valves, on
the other hand, provide higher dR/R and better exchange when the NiO AF material
is at the bottom. Therefore, combining the NiO based spin valve at the bottom
with the metallic AF (IrMn, PtMn, NiMn, etc.) based spin valve on the top would
provide better dual spin valve structures. One issue with the standard NiO spin
valve is the thermal stability. The NiO/NiFe interface does not withstand high
resetting temperatures (>240C) of metallic AF materials without significant loss
of dR/R (>20%). One solution to this problem is to utilize a CoFe/NiFe/CoFe
multilayered structure as the first pinned layer with the NiO AF material. This
pinned layer structure provides high thermal stability with NiO/CoFe interface
and lower coercivity with the addition of a NiFe layer. Therefore, a dual spin
valve sensor with the following structure would provide high GMR values with good
thermal stability. The structure is as follows:
NiO/CoFe/NiFe/CoFe/Ru/CoFe/Cu/CoFe/NiFe/CoFe/Cu/CoFe/Ru/CoFe/Met. AF/Ta where
metallic AF can be IrMn, PtMn, NiMn etc.

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