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SELF-PINNED TUNNEL VALVE WITH IN-STACK BIAS LAYER

IP.com Disclosure Number: IPCOM000016407D
Original Publication Date: 2002-Nov-07
Included in the Prior Art Database: 2003-Jun-21
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Abstract

Disclosed is a new structure for the CPP sensor. This sensor is either a Magnetic Tunnel Junction or a CPP GMR type. The magnetizations of the pinned layers of the sensor are SELF-PINNED perpendicular to the air bearing surface using the positive magnetostriction and compressive stress. The free layer of the sensor is stabilized by an in-stack bias layer. The magnetization of the n-stack bias layer can be pinned parallel to the air bearing surface by using negative magnetostriction and compressive stress. Example structures are shown below: First example, where self-pinning is used only for the pinned layers: Ta/PtMn/CoFe/Ru/CoFe/Al2O3/CoFe/NiFe/Ta/CoFe/PtMn/Ta The first PtMn is very thin 30A. The only purpose is to work as the seed layer for the sensor. The 2nd PtMn, which is on top of the CoFe bias layer is thick 150A) to provide pinning through exchange coupling.

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SELF-PINNED TUNNEL VALVE WITH IN-STACK BIAS LAYER

Disclosed is a new structure for the CPP sensor. This sensor is either a Magnetic Tunnel Junction or a CPP GMR type. The magnetizations of the pinned layers of the sensor are SELF-PINNED perpendicular to the air bearing surface using the positive magnetostriction and compressive stress. The free layer of the sensor is stabilized by an in-stack bias layer. The magnetization of the n-stack bias layer can be pinned parallel to the air bearing surface by using negative magnetostriction and compressive stress. Example structures are shown below:

First example, where self-pinning is used only for the pinned layers:

Ta/PtMn/CoFe/Ru/CoFe/Al2O3/CoFe/NiFe/Ta/CoFe/PtMn/Ta

The first PtMn is very thin < 30A. The only purpose is to work as the seed layer for the sensor. The 2nd PtMn, which is on top of the CoFe bias layer is thick (> 150A) to provide pinning through exchange coupling.

Second example, where self-pinning is used for both pinned layers and in-stack bias layer:

Ta/PtMn/CoFe/Ru/CoFe/Al2O3/CoFe/NiFe/Ta/CoFeX/Ru/CoFeX/Ta

Where X = Ni, Nb, the negative magnetostriction of the CoFeX layers provide magnetic anisotropy parallel to the air bearing surface for pinning the in-stack bias layer.

It should be noted that for CPP GMR, Al2O3 the barrier is replaced with conductive spacer like (Cu, Au, Ag). It is also understood that metals other than "Ta" can be used as the spacer layer between the free layer and the bias layer.

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