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Deactivation of Magnetic Material Beneath Conductor Leads in Magnetoresistive Sensor Structures

IP.com Disclosure Number: IPCOM000085954D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Gangulee, A: AUTHOR [+2]

Abstract

There is described deactivation of selected areas of magnetoresistive (MR) permalloy films by thermal diffusion in a small amount of vanadium.

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Deactivation of Magnetic Material Beneath Conductor Leads in Magnetoresistive Sensor Structures

There is described deactivation of selected areas of magnetoresistive (MR) permalloy films by thermal diffusion in a small amount of vanadium.

In many applications which utilize thin permalloy magnetoresistive stripes, such as bubble domain memory chips or thin film recording heads, it is desirable to deactivate the magnetic material under the conductor leads from noise and other considerations. Such magnetic material is invariably present when conductor leads are formed by electrodeposition, and is schematically shown in the drawing.

It has been suggested before that Cu or Cr should be deposited in immediate contact with the magnetic material before conductor deposition, and then the composite should be heat treated so as to diffuse the Cu or Cr atoms into the permalloy, thus increasing the coercivity and/or decreasing the magnetic moment, which effectively deactivates the magnetic material.

It has been determined that V is more effective than either Cr or Cu for this purpose. A comparison between the effectiveness of V and Cr (which in itself is more effective than Cu) is shown below, where 50 Angstroms of V or Cr was deposited on top of a 200 Angstroms thick permalloy film and the composite was annealed at 275 degrees C for 5 hours. Effect of Cr doping Effect of V doping Coercivity, H(c) increased 100 % increased 3000% Saturation Magnetization, M(s) decreased 10% de...