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Methods for Domain Optimization in Recording Heads

IP.com Disclosure Number: IPCOM000015626D
Original Publication Date: 2002-Jul-20
Included in the Prior Art Database: 2003-Jun-20
Document File: 3 page(s) / 156K

Publishing Venue

IBM

Abstract

Disclosed is a method for locally influencing the effective magnetic anisotropy in patterned magnetic devices leading to improved performance of inductive and magneto-resistive recording heads and related magnetic devices. The technique is based on locally changing the magnetic properties of patterned magnetic devices by locally adjusting the effective material composition, the physical structure, the mechanical stress distribution, or a combination of the methods mentioned above. The domain structure, or better, the effective magnetic anisotropy, in recording heads strongly influences the magnetic performance of heads used for data storage applications. For example domain instabilities in the magnetic shields adjacent to the magneto-resistive (MR) sensor contribute to degraded performance due to induced noise in the read back signal. Another application of the enclosed methods is the optimization of the domain structure in magnetic yokes for high-speed writing applications. The patterned thick magnetic films, used for magnetic shields and flux delivering parts in magnetic recording heads are strongly sensitive to stress relaxation at the edges and the air-bearing surface (ABS). The existing stress anisotropy can be of the order of several 100MPa and leads together with even small values of magnetostriction to large changes in magnetic anisotropy. A typical stress distribution in a patterned magnetic film used in recording heads together with the resulting stress anisotropy over one edge is shown in Fig.1. 0 20 40 6080100

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Page 1 of 3

Methods for Domain Optimization in Recording Heads

Disclosed is a method for locally influencing the effective magnetic anisotropy in
patterned magnetic devices leading to improved performance of inductive and
magneto-resistive recording heads and related magnetic devices. The technique is based
on locally changing the magnetic properties of patterned magnetic devices by locally
adjusting the effective material composition, the physical structure, the mechanical
stress distribution, or a combination of the methods mentioned above.

The domain structure, or better, the effective magnetic anisotropy, in recording heads
strongly influences the magnetic performance of heads used for data storage
applications. For example domain instabilities in the magnetic shields adjacent to the
magneto-resistive (MR) sensor contribute to degraded performance due to induced noise
in the read back signal. Another application of the enclosed methods is the
optimization of the domain structure in magnetic yokes for high-speed writing
applications.

The patterned thick magnetic films, used for magnetic shields and flux delivering
parts in magnetic recording heads are strongly sensitive to stress relaxation at the
edges and the air-bearing surface (ABS). The existing stress anisotropy can be of the
order of several 100MPa and leads together with even small values of magnetostriction
to large changes in magnetic anisotropy. A typical stress distribution in a patterned
magnetic film used in recording heads together with the resulting stress anisotropy
over one edge is shown in Fig.1.

0 20 40 6080100

distance from center [µm]

anisotropy

stress

relative

1.0

0.8

0.6

0.4

0.2

(a) (b)

  ferro- magnetic film

σ

ABS

0.0

σ

(c)

8345ideal case Ni Fe55 Ni Fe17

Fig. 1 (a) Typical stress distribution in a recording head. (b) Stress anisotropy
distribution close to an edge. (c) Resulting domain structures for typical stress and
magnetic property values of plated Ni83Fe17 and Ni45Fe55-films.

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The effective lateral magnetic anisotropy can be adjusted and controlled by modifyin...