JPH10214719A - Vertical magnetic recording medium and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable improvement of productivity in making small thickness of medium total thickness caused by a film thickness reduction of a magnetic domain controlling magnetic layer by providing with a magnetic recording layer made of hard magnetic material, a back layer made of soft magnetic material and a magnetic domain layer made of manganese back anti-ferromagnetic material to make the layer into a single magnetic domain. SOLUTION: A magnetic recording medium 20 is constituted of a soft magnetic back layer 22 locating under a hard magnetic recording layer 21, a magnetic domain controlling layer 23 made of ferromagnetic material which is provided under the back layer 22 and a substrate 24 provided under the magnetic domain controlling layer 23. A magnetic recording medium 20' having another constitution is constituted of a magnetic domain controlling layer 23' locating on the soft magnetic back layer 22 and a magnetic domain controlling layer 23' which is provided between the hard magnetic recording layer 21 and the soft magnetic back layer 22. As examples of manganese system anti-ferromagnetic material which can be used for the magnetic domain controlling layers 23 and 23' can be given binary alloy system which are represented by PdMn, PtMn and NiMn, and ternary alloy systems which are represented by PdPtMn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a magnetic recording medium. More specifically, the present invention relates to a two-layer film medium including a magnetic recording layer used for perpendicular magnetic recording and a soft magnetic underlayer.

[0002]

2. Description of the Related Art Perpendicular magnetic recording systems have attracted attention as a technique for meeting the recent demand for higher recording density. In addition, with the demand for such high-density recording, the recording medium itself is required to have low noise as well as high output in order to improve the SN ratio.

[0003] A perpendicular magnetic recording medium comprises a magnetic recording layer of a hard magnetic material and a backing layer of a soft magnetic material which plays a role of concentrating a magnetic flux used for recording on the recording layer.
Spike noise, which is one of the problems in the perpendicular magnetic recording medium having such a structure, is caused by the domain wall of the soft magnetic layer serving as the backing layer. Therefore, it is necessary to control the domain wall motion of the soft magnetic underlayer in order to reduce the noise of the perpendicular magnetic recording medium.

As shown in FIG. 1, in a conventional perpendicular magnetic recording medium 10, a soft magnetic underlayer 12 is disposed under a hard magnetic recording layer 11, and the soft magnetic underlayer 12
As a lower layer, a layer 13 of a hard magnetic material such as CoCrTa / Cr or CoSm is provided.
By making 2 a single magnetic domain, the movement of the domain wall was eliminated, and the influence of spike noise was suppressed. In order to control the magnetic domain of the soft magnetic underlayer 12 using the hard magnetic layer 13 for controlling the magnetic domain, the thickness of the hard magnetic layer 13 must be at least 100 n.
m was required.

[0005]

The thickness of such a conventional hard magnetic layer for controlling magnetic domains occupies about 15% of the total thickness of the magnetic layer of a magnetic recording medium, so that the total thickness of the medium increases. The time required for forming the magnetic layer by the sputtering technique becomes longer, which is disadvantageous for mass production.

Accordingly, the present invention provides an effective magnetic domain control effect of the soft magnetic underlayer, improves signal quality (reduces noise), and reduces the total thickness of the medium by reducing the thickness of the magnetic domain control magnetic layer. It is an object of the present invention to provide a new perpendicular magnetic recording medium capable of improving productivity by reducing the thickness.

[0007]

The perpendicular magnetic recording medium of the present invention comprises a magnetic recording layer of a hard magnetic material, a backing layer of a soft magnetic material, and a magnetic domain control layer for converting the backing layer into a single magnetic domain. And a manganese-based antiferromagnetic material is used as a material of the magnetic domain control layer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a perpendicular magnetic recording medium of the present invention,
The magnetic domain control layer of a manganese-based antiferromagnetic material may be provided as a lower layer of the soft magnetic underlayer, or may be provided thereon.

Referring to FIG. 2, the perpendicular magnetic recording medium of the present invention will be described. FIG. 2A shows an embodiment in which a magnetic domain control layer is provided as a lower layer of a soft magnetic backing layer. In the recording medium 20, a soft magnetic underlayer 22 is located below the hard magnetic recording layer 21, and a magnetic domain control layer 23 made of a manganese-based antiferromagnetic material is arranged below this underlayer 22. This layer configuration corresponds to the above-described layer configuration of the conventional perpendicular magnetic recording medium in which the hard magnetic material layer for controlling magnetic domains is replaced with a manganese-based antiferromagnetic material layer. Under the magnetic domain control layer 23, a substrate 24 supporting the entire magnetic layer is located.

FIG. 2B shows an embodiment in which the magnetic domain control layer is provided as an upper layer of the soft magnetic underlayer. In the magnetic recording medium 20 'of this embodiment, the magnetic domain control layer is provided on the soft magnetic underlayer 22. 23 ', that is, the magnetic domain control layer 2
3 'is disposed between the upper hard magnetic recording layer 21 and the lower soft magnetic underlayer 22. In this embodiment, the backing layer 22 concentrates magnetic flux on the recording layer 21.
Although it is not so advantageous for the function of the above, it is more advantageous to arrange the magnetic domain control layer 23 'of the manganese-based antiferromagnetic material as the upper layer of the backing layer 22 in terms of forming the backing layer 22 into a single magnetic domain. , And thereby the magnetic domain control layer 23 'can be made thinner. Under the backing layer 22 in this embodiment, there is a substrate 24 that supports the entire magnetic layer.

Examples of the manganese-based antiferromagnetic material that can be used as the material of the magnetic domain control layer in the magnetic recording medium of the present invention include binary alloys represented by PdMn, PtMn and NiMn, and PdPtMn. Ternary alloys.

For the ternary alloy system of PdPtMn, 4
An alloy composition in which 7 to 53 atomic% is Mn, 5 to 23 atomic% is Pt, and the balance is Pd is particularly effective. If a PdPtMn antiferromagnetic material having such a composition is used, the effect of controlling the magnetic domain of the soft magnetic layer can be sufficiently obtained with a film thickness of about 15 nm or more. As a result, in the conventional hard magnetic material, 10
The thickness of the magnetic domain control layer, which was required to be about 0 nm, can be reduced, so that productivity can be improved and manufacturing costs can be reduced.

The magnetic recording medium of the present invention can be easily manufactured by sequentially forming each magnetic layer on a suitable substrate by a sputtering technique in the same manner as the conventional one. The magnetization direction of the soft magnetic underlayer in contact with the antiferromagnetic layer is
It is controlled by heat treatment in a magnetic field and fixed in a certain direction. For example, by heating to an appropriate temperature in a radial magnetic field and then cooling, the backing layer can be given a magnetization direction corresponding to the radial magnetic field application direction. The temperature of this heat treatment is preferably set to 180 ° C. or higher.

[0014]

Next, the present invention will be further described with reference to examples.
Of course, the invention is not limited to these examples.

On a silicon substrate, as an underlayer,
4 nm of NiFe as a soft magnetic layer, and 2 mm of PdPtMn of various compositions as an antiferromagnetic layer.
Various samples were produced by laminating each layer by sputtering to a thickness of 5 nm. For these samples, 180, 200, 230, and 25 were applied while applying a DC magnetic field of 2.5 kOe in a vacuum having an ultimate vacuum of 1 × 10 ⁻⁴ Pa or less.
Heat treatment was performed at 0 and 300 ° C. for 1 hour. The magnetization curve of the heat-treated sample was measured at room temperature using a VSM apparatus, and a unidirectional anisotropic magnetic field (Hua) was calculated. This unidirectional anisotropic magnetic field is an index indicating a bias effect on the soft magnetic layer.

FIGS. 3 and 4 show the dependence of the unidirectional anisotropic magnetic field (Hua) on the Mn composition in the antiferromagnetic material and the P, respectively.
It shows t composition dependency. FIG. 3 shows Hua of the antiferromagnetic material when the composition ratio of Pd and Pt is 1: 1 and the Mn composition is changed. On the other hand, FIG.
% Is plotted with respect to the Pt content of Hua of the antiferromagnetic material when fixed to%. From the graphs of FIGS. 3 and 4, Mn is 47 to 53 at% and Pt is 5 to 23 at%.
It can be seen that Hua is developed in the PdPtMn antiferromagnetic layer by the heat treatment in the composition range described above.

FIG. 5 shows Hua of the PdPtMn antiferromagnetic layer.
Shows the temperature dependence of heat treatment.
Pd in which the largest Hua was expressed in the dependence study₃₀Pt₂₀
Mn ₅₀Was created for the composition of 180 ° C or less
By performing the heat treatment at the above temperature, Hu of 100 Oe or more can be obtained.
It can be seen that a is expressed.

FIG. 6 shows Hua of the PdPtMn antiferromagnetic layer.
This graph also shows the composition dependence.
Pd in which the largest Hua was expressed in the dependence study₃₀Pt₂₀
Mn ₅₀Was created for the composition of PdPtM
Hua develops after heat treatment even when the film thickness of n is 15 nm.
Can be confirmed.

It is considered that the NiFe soft magnetic layer, whose magnetization is saturated by an applied magnetic field of several Oe, has a single magnetic domain structure and the domain wall disappears due to the appearance of the unidirectional anisotropic magnetic field in PdPtMn after the heat treatment. Can be These results are for an experimental sample in which the NiFe soft magnetic layer is 4 nm, but the same principle can be applied to an actual recording medium by using a relatively thin manganese-based antiferromagnetic material of, for example, several tens nm. Thus, an effect of making the soft magnetic layer a single magnetic domain can be expected.

[0020]

As described above, according to the present invention,
The magnetic domain of the soft magnetic backing layer for noise reduction in perpendicular magnetic recording media can be controlled with a relatively thin manganese-based antiferromagnetic layer, reducing the total thickness of the media, reducing manufacturing costs and manufacturing time. It greatly contributes to the improvement of productivity by shortening the time.

[Brief description of the drawings]

FIG. 1 is a structural explanatory view of a conventional perpendicular magnetic recording medium.

FIG. 2 is an explanatory view of a structure of a perpendicular magnetic recording medium of the present invention, wherein (a) shows a structure of an embodiment in which a magnetic domain control layer made of an antiferromagnetic material is provided below a soft magnetic underlayer. ,
(B) shows a structure in which a magnetic domain control layer made of an antiferromagnetic material is provided on a soft magnetic underlayer.

FIG. 3 is a graph showing the dependence of the unidirectional anisotropic magnetic field (Hua) on the Mn composition in a PdPtMn antiferromagnetic material.

FIG. 4 is a graph showing a Pt composition dependency of a unidirectional anisotropic magnetic field (Hua) in a PdPtMn antiferromagnetic material.

FIG. 5 is a graph showing the heat treatment temperature dependence of Hua in a PdPtMn antiferromagnetic layer.

FIG. 6 is a graph showing a Hua film thickness dependency of a PdPtMn antiferromagnetic layer.

[Explanation of symbols]

 10, 20, 20 ': perpendicular magnetic recording medium 11, 21, hard magnetic recording layer 12, 22: soft magnetic backing layer 13: hard magnetic layer for controlling magnetic domains 23, 23': antiferromagnetic layer for controlling magnetic domains 24: substrate

Claims (7)

[Claims] 1. A magnetic recording layer of a hard magnetic material, a backing layer of a soft magnetic material, and a magnetic domain control layer for converting the backing layer into a single magnetic domain. A perpendicular magnetic recording medium using a magnetic material. 2. The perpendicular magnetic recording medium according to claim 1, wherein the magnetic domain control layer is provided as a lower layer of the soft magnetic underlayer. 3. The perpendicular magnetic recording medium according to claim 1, wherein the magnetic domain control layer is provided as an upper layer of the soft magnetic underlayer. 4. The manganese-based antiferromagnetic material of the magnetic domain control layer is a binary alloy of PdMn, PtMn or NiMn,
4. The perpendicular magnetic recording medium according to claim 2, wherein the perpendicular magnetic recording medium is a ternary alloy of PdPtMn. 5. The method according to claim 1, wherein the manganese-based antiferromagnetic material is PdPt.
A ternary alloy of Mn, with 47 to 53 atomic% of Mn,
5. The perpendicular magnetic recording medium according to claim 4, wherein the composition has a composition of 23 atomic% of Pt and the balance of Pd. 6. The perpendicular magnetic recording medium according to claim 5, wherein the thickness of the magnetic domain control layer is 15 nm or more. 7. A magnetic recording layer of a hard magnetic material, a backing layer of a soft magnetic material, and a magnetic domain control layer made of a manganese-based antiferromagnetic material for contacting the backing layer and making the backing layer a single magnetic domain. And fixing the magnetization direction of the soft magnetic material backing layer in contact with the magnetic domain control layer by performing a heat treatment at a temperature of 180 ° C. or more in a magnetic field. Perpendicular magnetic recording medium manufacturing method.