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NiCo/NiFe Multilayer Structures

IP.com Disclosure Number: IPCOM000115733D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Gill, H: AUTHOR [+3]

Abstract

NiCo and NiFeCo alloys possess high anistropic magnetoresistance (4 to 5%) compared to standard NiFe (80/20%) films. However, large anistropy fields (15 to 20 Oe) and large negative magnetostriction make these materials unattractive to be used as MagnetoResistive (MR) sensor material. Our earlier studies have shown that the anistropy field of NiFeCo thin films can be reduced by up to 30% if deposition is done using Ion Beam Sputter Deposition (IBSD) technique. Although different target compositions were tried, the films all showed moderately high negative magnetosriction (lambda).

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NiCo/NiFe Multilayer Structures

      NiCo and NiFeCo alloys possess high anistropic
magnetoresistance (4 to 5%) compared to standard NiFe (80/20%) films.
However, large anistropy fields (15 to 20 Oe) and large negative
magnetostriction make these materials unattractive to be used as
MagnetoResistive (MR) sensor material.  Our earlier studies have
shown that the anistropy field of NiFeCo thin films can be reduced by
up to 30% if deposition is done using Ion Beam Sputter Deposition
(IBSD) technique.  Although different target compositions were tried,
the films all showed moderately high negative magnetosriction
(lambda).

      In this study, NiFe/NiCo multilayer structures were deposited
using IBSD in various forms to obtain zero magnetostriction while
enhancing the MR coefficient (dR/R).  Target compositions used were
76.5-23.5% (large positive lambda) and 70-30% (large negative lambda)
for Ni-Fe and Ni-Co respectively.  The total magnetic thickness of
the multilayer structures were around  150 to 200 A and individual
layer thickness' ranged from 15 to 50 A. The results showed that the
magnetostriction of the NiCo/NiFe multilayer structure can be
adjusted by simply changing the relative thickness or percentage of
each layer (rule of mixture) in the structure.  This linear
correlation holds in the full range of our study as shown in the
Figure where NiCo thickness was changed from 14 to 38% of the total
thickness.  This linear dependence was also independent of the number
of layers or layer thickness.  These findings are in contrast with
the earlier report by [*]  multilayered NiFe structures where they
have seen that the magnetostrictio...