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Magnetoresistive Element Film Bias

IP.com Disclosure Number: IPCOM000050724D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Chow, WW: AUTHOR [+3]

Abstract

Permalloy films can provide an easy axis bias to a magnetoresistive (MR) sensor using the DC current directed to the element to drive the film. The film is formed in the shape of a C-magnet with a small gap between the ends of the magnet and the MR element.

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Magnetoresistive Element Film Bias

Permalloy films can provide an easy axis bias to a magnetoresistive (MR) sensor using the DC current directed to the element to drive the film. The film is formed in the shape of a C-magnet with a small gap between the ends of the magnet and the MR element.

As shown in the figure, an MR element 1 has a bidirectional current directed through it by virtue of a center-tapped conductor 2 and return conductors 3 and 4 connected at the ends of the MR element 1. A film of a nickel-iron material is deposited in the shape of a C-magnet 5 on the same plane as the MR element L. The C-magnet 5 has its poles 6 and 7 separated by a non-magnetic gap 8 and 9, respectively. A portion of the center-tapped conductor 2 is wrapped around the base of the C-magnet 5 to form a coil identified by reference numeral 10. The current I directed into the center-tapped conductor 2 sets up a field in the C- magnet 5 by virtue of the coil 10 to provide an easy axis bias field to the MR element 1.

The number of turns wrapped around the C-magnet can be varied to produce the amount of bias field necessary for the MR element 1. The generation of the magnetic field into the C-magnet 5 could be produced without the coil 10 by the placement of the conductor 2 on one side of the C-magnet 5 and the return conductors 3 and 4 on the other side. Likewise in a non-center tapped MR head, each conductor may be placed on opposite sides of the C-magnet 5 to produce the necessar...