JPS629518A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To prevent the decrease of S/N by noise by forming a soft magnetic film having the coercive force of a specific value or below in such a manner that the magnitude of the residual magnetization under data tracks is larger than the magnitude of the residual magnetization under guard band tracks. CONSTITUTION:A nickel phosphorus film 4 having <=50Oe coercive force is formed as the soft magnetic film on the surface of a substrate 6 and the magnetic film 3 having vertical magnetic anisotropy is formed on the film 4. Laser light is irradiated to the region corresponding to the data tracks 1 to heat said region after or prior to the formation of the film 3 by which the part of the film 4 under the data tracks is crystallized and a high residual magnetization region 5 having the increased residual magnetization and soft magnetization is provided. The output from the record to the guard band tracks 2 between the data tracks 1 is thus made substantially smaller than the output from the data tracks 1 by the deviation of tracking and the crosstalk from the recording region by the deviation of the tracking in the adjacent tracks is suppressed. The signal having large S/N is thereby obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a magnetic recording medium that magnetically records data, and in particular to a magnetic recording medium that records data by perpendicular magnetic recording. The present invention relates to a magnetic recording medium with improved off-track characteristics related to problematic tracking accuracy and a method for manufacturing the same.

(Prior art and its problems) Improving the recording density of magnetic recording devices is a constant trend in the field. The magnetic recording bodies used in conventional magnetic recording devices generally perform recording and reproduction by magnetizing in the longitudinal direction of the recording medium, but as the density increases, there is a limit to the recording density due to the influence of the demagnetizing field, and higher density is possible. A perpendicular magnetic recording system has been proposed in which the recording medium is magnetized perpendicularly to the surface of the medium, and has achieved a recording density one order of magnitude higher than that of the conventional method.

The perpendicular magnetic recording medium used here is a CoCr single-layer perpendicular medium formed by sputtering or vapor deposition, and a CoCr/Ni permalloy (NiFe) base film.
There is a Fe two-layer film medium. Among these, double-layer perpendicular media enable ideal perpendicular recording and achieve high-density recording by combining a single-pole type perpendicular head equipped with a magnetic flux return path.

In this way, in the perpendicular magnetic recording method, it is possible to significantly improve the linear density in the track direction on the recording medium surface by giving the medium perpendicular magnetic anisotropy. In order to improve
It is necessary to increase the density by more than an order of magnitude. As the track density increases, it is not possible to obtain sufficient tracking and king accuracy, which causes noise due to unerased parts, and 87N ratio (S: signal, N: noise ) arises.

(Object of the Invention) An object of the present invention is to solve the above-mentioned problems, form a magnetic film having magnetic anisotropy perpendicularly to the surface of a soft magnetic film formed on a substrate, and form a magnetic film with magnetic anisotropy under the data track. By making the magnitude of the residual magnetization larger than the value of the residual magnetization of the soft magnetic film under the guard band track, noise is prevented and the S/
An object of the present invention is to provide a magnetic recording medium with improved N ratio and a method for manufacturing the same.

(Structure of the Invention) The present invention provides magnetic recording in which a soft magnetic film with a coercive force of 50 Oe or less is formed on a substrate, and a magnetic film having magnetic anisotropy perpendicular to the film surface is formed on the soft magnetic film. In the magnetic field, it is assumed that the magnitude of residual magnetization in a portion of the soft magnetic film under the data track is larger than the magnitude of residual magnetization in a portion under the guard band track between the data tracks.

The method for manufacturing a magnetic recording body of the present invention includes a soft magnetic film forming means for forming a soft magnetic film on a substrate, and a magnetic film forming means for forming a magnetic film having magnetic anisotropy perpendicular to the film surface on the soft magnetic film. The apparatus includes a film forming means, and a heating means for irradiating light to heat at least a region corresponding to a data track of the base body on which the soft magnetic film is formed.

(Example) Next, the present invention will be explained using the drawings.

1 and 2 are a perspective view schematically showing a partially cut away magnetic disk according to an embodiment of the present invention, and a perspective view showing a manufacturing method thereof, respectively.

By electroless or electrolytic plating, magnetism appears or increases on the surface of the substrate 6 made of aluminum alloy or the like by annealing at a relatively low temperature (150 to 200° C.).

After forming the Kellin film 4 as a soft magnetic film, and forming a magnetic film 3 having magnetic anisotropy perpendicularly on the Kellin film 4, or prior to forming the magnetic film 3, an area corresponding to the data track IK is formed. By irradiating and heating the nickel phosphorus film 4 with laser light as shown in FIG. establish.

When a main pole excitation type perpendicular head is used in the embodiment shown in FIG. 1, the recording and reproducing sensitivity is greatly increased in the data track L by making the high residual magnetization region 5 of the nickel phosphorus film 4 soft magnetic. This makes it possible to obtain high output and perform high-density recording.

As a result, the output from recording on guard band track 2 between data tracks 1 can be made sufficiently smaller than the output from data track 1 due to tracking deviation, and crosstalk from the recording area due to tracking deviation in adjacent tracks can also be suppressed. A signal with a large S/N ratio can be obtained.

In the example shown in FIG. 1, a 10 μm thick nickel phosphorous film 4 was formed on an aluminum alloy substrate 6 by electroless plating. The residual magnetization of the formed nickel phosphorus film 4 is 3 Q em
It was u/cc. The substrate containing the nickel phosphorus film 4 was polished to a surface roughness normally used as a magnetic disk substrate. On the polished substrate, a CoCr target was sputtered to a thickness of 0.2 μm. A magnetic film 3 was formed. The residual magnetization Ms of this magnetic film 3 is 30 Oemu/CC*
The vertical coercive force HCL was 500 Oe.

Next, as shown in FIG. 2, the substrate is rotated, and CO:
Laser light 7 from a laser irradiation device 8 was focused by a lens 9 and irradiated to heat it.

The residual magnetization of the nickel phosphorus film in the area heated by laser light under the same conditions increased to 200 emu/ee, and the coercive force was 10 Oe.◎ To confirm the effect, the data track of the example shown in Figure 1 was used. The recording and reproducing characteristics of Sample No. 1 and Gartband Track 2 were measured using a main pole excitation perpendicular magnetic head having a return path structure for magnetic flux from the main pole to the medium. A CoZrNb film with a thickness of 0.3 μm was used as the main pole film. The results are shown in Figure 3 (curve 10 is the data track 19 curve 11).
shows the characteristics of the guard band track 2), on the data track 1, the recording density Dso of the output that is 1/2 of the solitary wave output is 5oKFRPI, while on the guard band track 2, the recording density Dso is 1/2 of the solitary wave output. The recording density I)io at an output of /2 was 50 KF PI. Also, the output was 2.3 times greater on data track 1 than on gartband track 2.

Therefore, at a recording density of 5oKFRPI or higher on data track 1, the playback output from guard band track 2 can be made sufficiently smaller than the output of data track 1, and by defining data track 1 on the media surface, good off-track characteristics can be achieved. I was able to get it.

Furthermore, the recording/reproducing output of the embodiment shown in FIG.
As shown in FIG. 4, the coercive force of the soft magnetic film 4 increased below 50 Oe.

In addition, in the manufacturing method of the embodiment shown in FIG.
Alternatively, the nickel-phosphorous film 4 may be formed on the substrate 6 and heated by the laser beam 7, and then the magnetic film 3 may be heated.
may be formed.

(Effects of the Invention) As explained above, the present invention forms a magnetic film having magnetic anisotropy perpendicular to the film surface on a soft magnetic film, and reduces the residual magnetization of the portion of the soft magnetic film below the data track. By making the size larger than the residual magnetization of the portion under the guard band track, the reproduction output from the guard band track can be sufficiently reduced, and crosstalk from adjacent tracks can be suppressed.

[Brief explanation of the drawing]

1 and 2 are a perspective view showing a part of an embodiment of the present invention and a perspective view showing a manufacturing method thereof, and FIGS. 3 and 4 are respectively recording and reproducing of the embodiment shown in FIG. 1. 2 is a graph showing the relationship between output and recording density, and a graph showing the relationship between output and coercive force of a nickel phosphorus film. 1... Data track, 2... Guard band track, 3... Magnetic film, 4...
・Nickel phosphorus film, 5... High remanent magnetization region, 6
...Substrate, 7...Laser light, 8...
... Laser irradiation device, 9... Lens. ! : Data Track 2:f)”-Tono V Ladotra Sof3
J-4: At 41, the date is 5.
: 關田纜佽, b:1+ lute l ward! l: data track otsu: base 7: p-tr 6 S shizu°'-terumi size L 82-zu Kiku'1g degree (KFRPI)

Claims (2)

[Claims] (1) In a magnetic recording body in which a soft magnetic film having a coercive force of 50 Oe or less is formed on a substrate, and a magnetic film having magnetic anisotropy perpendicular to the film surface is formed on the soft magnetic film, the soft magnetic A magnetic recording body characterized in that the magnitude of residual magnetization in a portion of the film under the data track is larger than the magnitude of residual magnetization in the portion under the guard band track between the data tracks. (2) a soft magnetic film forming means for forming a soft magnetic film on a substrate; a magnetic film forming means for forming a magnetic film having magnetic anisotropy perpendicular to the film surface on the soft magnetic film; A method for manufacturing a magnetic recording body, comprising: heating means for heating an area corresponding to a data track of the base on which a soft magnetic film is formed by irradiating light.