Browse Prior Art Database

DOUBLE DUAL GMR HEAD

IP.com Disclosure Number: IPCOM000013305D
Original Publication Date: 2000-Jan-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 1 page(s) / 24K

Publishing Venue

IBM

Abstract

A new design for the GMR is disclosed to enhance the magnetoresistance coefficient. The design utilizes two FREE layers to enhance the spin dependent scattering to achieve higher magnetoresistance.

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DOUBLE DUAL GMR HEAD

   A new design for the GMR is disclosed to enhance the magnetoresistance
coefficient. The design utilizes two FREE layers to enhance the spin dependent
scattering to achieve higher magnetoresistance.

The first structure utilizes three antiferromagnetic layers to provide pinning to
four antiparallel pinned ferromagnetic layers as shown below. The middle
antiferromagnetic layer is shared by the two antiparallel pinned layers.

Seed layer/AFM/FM(1)/Ru/FM(2)/Cu/Free
layer/Cu/FM(3)/Ru/FM(4)/AFM/FM(5)/Ru/FM(6)/Cu/Free layer/Cu/FM(7)/Ru/FM(8)/AFM/Ta

Seed layer examples: NiMnO/Ta, Ta, Al2O3/NiMnO/Ta

Ferromagnetic (FM) layer examples: CoFe, NiFe, Co

Antiferromagnetic (AFM) layer examples: PtMn, NiMn, IrMn

Free layer examples: CoFe/NiFe/CoFe

All AFMs are oriented in the same direction so that the pinned ferromagnetic
layers are in phase. This leads to in-phase signal from the "Free" layers. The
signal asymmetry is independent of the sense current magnitude or polarity due to
symmetrical location of two "Free" layers in the structure.

In the second embodiment, the middle layers FM(4)/AFM/FM(5) are replaced with one
FM layer creating an antiparallel pinned layer. The layers in the middle can be
oriented in the desired direction by proper combination of thicknesses and field
from the current.

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