Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2003-01-06
2004-09-21
Renner, Craig A. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06795273
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to magnetic recording, and more particularly, to a magnetic recording head with a multilayer, high moment structure.
BACKGROUND OF THE INVENTION
Magnetic recording heads have utility in a magnetic disc drive storage system. Most magnetic recording heads used in such systems today are “longitudinal” magnetic recording heads. Longitudinal magnetic recording in its conventional form has been projected to suffer from superparamagnetic instabilities at densities above approximately 40 Gbit/in
2
. It is believed that reducing or changing the bit cell aspect ratio will extend this limit up to approximately 100 Gbit/in
2
. However, for recording densities above 100 Gbit/in
2
, different approaches will likely be necessary to overcome the limitations of longitudinal magnetic recording.
An alternative to longitudinal recording is “perpendicular” magnetic recording. Perpendicular magnetic recording is believed to have the capability of extending recording densities well beyond the limits of longitudinal magnetic recording. Perpendicular magnetic recording heads for use with a perpendicular magnetic storage medium may include a pair of magnetically coupled poles, including a write pole having a small bottom surface area and a flux return pole having a larger bottom surface area. A coil having a plurality of turns is located adjacent to the write pole for inducing a magnetic field between that pole and a soft underlayer of the storage media. The soft underlayer is located below the hard magnetic recording layer of the storage media and enhances the amplitude of the field produced by the main pole. This, in turn, allows the use of storage media with higher coercive force, consequently, more stable bits can be stored in the media. In the recording process, an electrical current in the coil energizes the main pole, which produces a magnetic field. The image of this field is produced in the soft underlayer to enhance the field strength produced in the magnetic media. The flux density that diverges from the tip into the soft underlayer returns through the return flux pole. The return pole is located sufficiently far apart from the main write pole such that the material of the return pole does not affect the magnetic flux of the main write pole, which is directed vertically into the hard layer and the soft underlayer of the storage media.
Saturation magnetization is an important property of recording heads and is directly related to the areal density that may be achieved by a head-media combination. Therefore, in selecting a material or structure to form at least a portion of either a write pole of a longitudinal recording head or the write pole of a perpendicular magnetic recording head, it is desirable to have a material or structure that exhibits a large/high saturation magnetization (4&pgr;M
s
), also generally referred to as “moment” or “magnetic moment”. For example, one of the highest known saturation magnetizations at room temperature is exhibited by the bulk alloy Fe
65
Co
35
which has a saturation magnetization value of approximately 2.45T. In view of the desire to continuously increase the areal density, it would be advantageous, therefore, to have a material or structure that has an enhanced or increased saturation magnetization value.
There is identified, therefore, a need for an improved magnetic recording head that overcomes limitations, disadvantages, and/or shortcomings of known magnetic recording heads. There is also identified a need for an improved material or structure having an enhanced saturation magnetization or moment in comparison to known materials or structures.
SUMMARY OF THE INVENTION
Embodiments of the invention meet the identified need, as well as other needs, as will be more fully understood following a review of the specification and drawings.
In accordance with an aspect of the invention, a magnetic recording head comprises a write pole having alternating layers of Fe and Co, and a return pole magnetically coupled to the write pole. The layers of Fe may have a thickness from about 1.0 angstroms to about 40.0 angstroms and the layers of Co may have a thickness from about 1.0 angstroms to about 20.0 angstroms. The write pole is able to achieve a saturation magnetization greater than about 2.45 Tesla.
In accordance with another aspect of the invention, an enhanced moment magnetic structure comprises a multilayer structure having alternating layers of xÅFe and yÅCo, wherein 1.0≦x≦40.0 and 1.0≦y≦20.0. The multilayer structure may have a thickness from about 50 angstroms to about 5,000 angstroms and is able to obtain a saturation magnetization greater than about 2.45 Tesla.
In accordance with yet another aspect of the invention, a method for forming a write pole for a magnetic recording head comprises depositing a layer of Fe on a substrate, depositing a layer of Co on the layer of Fe and then depositing additional layers of Fe and Co to form a multilayer structure. The depositing of the layers of Fe and Co may be performed by a physical vapor deposition process. The layers of Fe are deposited to have a thickness in the range from about 1.0 angstroms to about 40.0 angstroms and the layers of Co are deposited to have a thickness in the range from about 1.0 angstroms to about 20.0 angstroms. The write pole is formed to have a saturation magnetization greater than about 2.45 Tesla.
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Freeman Arthur J.
Klemmer Timothy J.
Minor Michael K.
Seigler Michael A.
Pietragallo Bosick & Gordon
Quantum Materials Design, Inc.
Queen, II Benjamin T.
Renner Craig A.
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