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High 4_Ms Soft Magnetic Multilayer Structures with Tunable, Near Zero Magnetostriction

IP.com Disclosure Number: IPCOM000110079D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 3 page(s) / 119K

Publishing Venue

IBM

Related People

Jahnes, CV: AUTHOR [+6]

Abstract

As magnetic storage products drive towards higher aerial densities and data rates, advanced soft materials and structures are required to make higher performance recording heads (inductive and/or other types). Permalloy (typically the Ni80Fe20 composition) has been the material of choice for recording heads for many years. It possesses a desirable balance of relatively high magnetization (4fM5 N 10,000 G), low coercivity (Hc < 1 Oe), relatively high permeability (2000 < m < 3000) and controllable near zero magnetostriction (gs). It is desirable to have a higher 4fMs than that of permalloy to facilitate the write process on high coercivity recording media and higher permeability to provide higher readback signals for inductive heads.

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High 4_Ms Soft Magnetic Multilayer Structures with Tunable, Near Zero Magnetostriction

       As magnetic storage products drive towards higher aerial
densities and data rates, advanced soft materials and structures are
required to make higher performance recording heads (inductive and/or
other types).  Permalloy (typically the Ni80Fe20 composition) has
been the material of choice for recording heads for many years.  It
possesses a desirable balance of relatively high magnetization (4fM5
N 10,000 G), low coercivity (Hc < 1 Oe), relatively high permeability
(2000 < m < 3000) and controllable near zero magnetostriction (gs).
It is desirable to have a higher 4fMs than that of permalloy to
facilitate the write process on high coercivity recording media and
higher permeability to provide higher readback signals for inductive
heads.  A second advantage of higher 4fMs materials is realized in
actual head fabrication where a pole tip thickness of from 3 to 4 mm
is needed to provide sufficient write magnetization but pole tip
trimming, usually by ion milling, becomes a time-intensive process
for materials this thick.  If the same magnetization could be
obtained with thinner pole tips, ion milling time would be decreased
and the fabrication process enhanced.  There are several soft
magnetic materials known which have higher 4fMs than Ni80Fe20,
particularly those based on iron which is the element with the
highest 4fMs.  However, other factors, such as high Hc and in
particular high gs, have limited practical application of these
materials.

      Recently (1,2) it has been demonstrated that when small amounts
of N2 are incorporated into iron thin films, an unexpectedly high
4fMs of > 25,000 G can be achieved as seen in in Fig. 1 for
films made in the laboratory. It has also been shown that lamination
of iron films with paramagnetic iron nitride (i.e., sufficient
nitrogen content to render the film non-ferromagnetic) can produce
films near zero gs (3).  In this case it is necessary to have the
laminate consist of N 30% non-magnetic material (see Figs. 2 and 3 of
(3).  It has also been reported that the gs of monolithic FeN films
varies with nitrogen content as shown in Fig. 5 of (4), although the
films in that work do not exhibit the enhanced 4fMs over Fe alone one
would expect with nitrogen incorporation.

      It has been discovered that not only does the gs of monolithic
FeN films vary as a function of nitrogen content but also as a
function of thickness a...