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Magneto-Resistive Head Design for More Uniformity of Sensitivity and Asymmetry

IP.com Disclosure Number: IPCOM000111010D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Cunningham, EA: AUTHOR

Abstract

A method is disclosed that improves the uniformity of current density in a Magneto-Resistive (MR) read element, where it would normally be non-uniform due to the finite resistivity of the contact leads.

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This is the abbreviated version, containing approximately 52% of the total text.

Magneto-Resistive Head Design for More Uniformity of Sensitivity
and Asymmetry

      A method is disclosed that improves the uniformity of current
density in a Magneto-Resistive (MR) read element, where it would
normally be non-uniform due to the finite resistivity of the contact
leads.

      A Magneto-Resistive (MR) read element is normally constructed
by having broad vertical thin-film leads come down over or adjacent
to a rectangular shaped thin-film set of layers that make up the
active area of the MR read element.  This forms a "U" shaped
structure with square corners, where the bias current for the MR
element must flow.  In the ideal case, the leads would have high
conductivity compared to the MR element, thus providing equipotential
contacts on each end of the MR element.  The resulting current flow
in the element would thus be perfectly uniform, in a horizontal
direction as described.  However, in the real case, the leads are not
perfect conductors and do not provide equipotentials at the ends of
the element.  The finite potential drop across the lead material
makes the total voltage drop across the top of the element, or inner
edge of the "U", larger than the drop across the lower edge of the
element.  Thus, the current density entering the top corners of the
element are higher than that at the lower edges, giving a non-uniform
distribution of current in the element.  As the current passes
through the stripe, the distribution evens out somewhat near...