Browse Prior Art Database

CPP GMR/TV IN DIFFERENTIAL MODE

IP.com Disclosure Number: IPCOM000010279D
Original Publication Date: 2002-Nov-14
Included in the Prior Art Database: 2002-Nov-14
Document File: 1 page(s) / 38K

Publishing Venue

IBM

Abstract

The CPP GMR or Tunnel Valve sensor disclosed here functions as a differential sensor with common SELF-PINNED layers also serving as the common electrode for this sensor. This sensor rejects common mode noise while the signals from the two sensors are added. The common self-pinned layer is AP-Coupled (CoFe/Ru/CoFe) where 180 degree out of phase magnetizations of the two CoFe layers provide 180 degree out of phase signals which are added in differential detection while commom mode noise (e.g. noise from thermal asperity or sensor heating) is rejected. The self-pinning is achieved by providing large positive magnetostriction of CoFe layers (E.g. Co60Fe40 alloy provides large positive magnetostriction) together with the compressive stress at the air bearing surface. This combination generates magnetic easy axis perpendicular to the air bearing surface for the pinned layers.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 1

CPP GMR/TV IN DIFFERENTIAL MODE

The CPP GMR or Tunnel Valve sensor disclosed here functions as a differential sensor with common SELF-PINNED layers also serving as the common electrode for this sensor. This sensor rejects common mode noise while the signals from the sensors are added. The common self-pinned layer is AP-Coupled (CoFe/Ru/CoFe) where 180 degree out of phase magnetizations of the two CoFe layers provide 180 degree out of phase signals which are added in differential detection while common mode noise (e.g. noise from the thermal asperity or sensor heating) is rejected. The self-pinning is achieved by providing large positive magnetostriction of CoFe (E.g. Co60Fe40 alloy provides large positive magnetostriction) together with the compressive stress at the air bearing surface. The combination generates magnetic easy axis perpendicular to the air bearing surface of the pinned layers.

The sensor layers are shown below:

Bottom shield(lead)/Ta/Cu/NiFe/CoFe/MgO or Al2O3/CoFe/Ru/CoFe/MgO or Al2O3/CoFe/NiFe/Cu/Ta/Top shield(Lead)

For CPP GMR insulating barriers can be replaced with cooper spacer.

Bottom shield, top shield, and middle self-pinned layers are three output terminals for this sensor.

Disclosed by International Business Machines Corporation

1