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Tailoring of Magnetic Exchange Bias by Use of Multilayered Ferro Magnetic-Antiferromagnetic Structures

IP.com Disclosure Number: IPCOM000100786D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Parkin, SSP: AUTHOR [+2]

Abstract

Disclosed is a method to produce a controllable, enhanced exchange bias field in ferromagnetic-antiferromagnetic multilayered structures by varying the number of interfaces per unit film thickness.

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Tailoring of Magnetic Exchange Bias by Use of Multilayered Ferro Magnetic-Antiferromagnetic Structures

       Disclosed is a method to produce a controllable, enhanced
exchange bias field in ferromagnetic-antiferromagnetic multilayered
structures by varying the number of interfaces per unit film
thickness.

      The phenomenon of exchange coupling between a ferromagnetic
layer and an antiferromagnetic layer is well known.  The most direct
manifestation of such a coupling is a magnetic hysteresis loop
shifted from zero field by a "bias field" [1].  It has been proposed
that this effect could be used to reduce Barkausen noise in permalloy
thin film magnetoresistive (MR) elements by coupling to an
antiferromagnetic layer, typically Fe50Mn50 [2].  Consider a device
containing a permalloy element.  In such a device, the permalloy
element has typically a thickness in the range of several hundred
angstroms such that under optimum processing conditions, exchange
bias fields of approximately 40-50 Oe can be obtained with Fe50Mn50 .
While such fields are acceptable, larger exchange bias fields allow
for larger device tolerances, and larger exchange bias fields are
required in applications in which the magnetic state of relatively
thick ferromagnetic layers has to be controlled.

      The method described here produces a magnetic exchange bias
field which can be varied by at least an order of magnitude for the
same total thickness of the ferromagnetic material.  This is achieved
by depositing a multilayered structure consisting of alternating
layers of ferromagnetic and antiferromagnetic material.  For example,
sputter-deposited multi...