JPS61199224A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium which is improved in the crystal orientation of a magnetic medium layer and is improved in magnetic characteristics and the number of times of CSS by providing a specific nonmagnetic underlying layer on a nonmagnetic substrate via a nonmagnetic hardened layer and providing the magnetic medium layer on the nonmagnetic underlying layer. CONSTITUTION:The nonmagnetic hardened layer 2 consisting of an alumite film, etc. is formed on the nonmagnetic substrate 1 consisting of an Al alloy, etc. in order to improve the surface characteristic of the substrate 1 and the surface of said layer is finished to a specular surface. The nonmagnetic underlying layer 3 is then formed by using one kind among TiO2, TiC and TiN on the layer 2 within the range of 50-2,400Angstrom film thickness. The magnetic medium layer 4 consisting of thin gamma-Fe2O3, Co and Co alloy thin films, etc. is formed on the layer 3. The crystal orientation and magnetic characteristics of the layer are made better by providing the layer 3 than in the case of forming directly the magnetic medium layer 4 on the layer 2. The high reliability magnetic disk or the like which increases the number of times of CSS is thus obtd.

Description

[Detailed description of the invention] [Industrial application field] This invention applies, for example, to cobalt and cobalt alloys.

The present invention relates to a magnetic recording medium having a magnetic layer made of a metal ferromagnetic material such as iron, iron alloy, nickel, or nickel alloy, or a magnetic layer made of a metal oxide ferromagnetic material such as iron oxide or chromium oxide.

[Conventional technology]

In recent years, the importance of external storage devices such as magnetic disks in computer systems has increased, and the demand for higher recording densities is increasing.

A magnetic recording device is composed of the main components of a recording/reproducing head and a magnetic disk.The 1A disk rotates at high speed, and the recording/reproducing head floats a minute distance above the magnetic disk. As the performance of magnetic recording devices improves, the load on the recording and reproducing head is reduced in order to reduce the flying distance, and contact start/stop (contact start/stop) is used.
08B) type head system is adopted. In order to increase the recording density and performance of magnetic disks, that is, magnetic recording media, it is necessary to make the recording media thinner and more uniform.

Improved magnetic properties (improved coercive force and squareness ratio) and improved disk surface precision to ensure stable head flying at low flying heights and prevent head-disk collisions (head crashes).

It is necessary to improve head crush resistance, etc.

Accordingly, it has become important to improve the quality of the substrate that supports the magnetic medium layer.

Conditions for a substrate suitable for high-density recording include good mechanical flatness and surface roughness, and a small number of defects. Furthermore, as the recording medium becomes thinner, the substrate needs to have sufficient hardness. In other words, if the substrate is soft, it will cause deformation such as depression when the magnetic head is connected to the magnetic disk, and not only will it be impossible to obtain a stable floating state of the magnetic head, but also the contact start/stop (which indicates the reliability of the magnetic recording device) will occur. aSS) There is a problem that the number of times becomes small.

Traditionally, aluminum alloys have been used for the substrates of magnetic disks, but this is done in order to achieve surface hardening and surface precision.

A hardened layer is coated thereon. For this hardened layer, a Ni-P plating film or an alumite film with good abrasiveness has been used (for example, Electric Corporation Research and Practical Application Report Vol. 31, No. 9, IT pages 31-1T44, Prior Art Patent Application No. 59-88
No. 633, Japanese Patent Application No. 1468). After forming this film, two machining processes are performed to improve the surface precision and form a magnetic medium layer. There is a close relationship between the magnetic properties and crystal orientation of this magnetic medium layer, and it is known that the crystal orientation is influenced by the type of underlying film of the magnetic medium layer (for example, Ota et al. Abstracts of Academic Lectures of the Japan Society of Applied Magnetics,
15PE-8 (1984)). For example, r-Fe20
3 thin film has [1)1] orientation.

It is known that in the case of c(1 and CQ alloy thin films), magnetic properties are better when the C-axis is oriented.

[Problem that the invention seeks to solve]

However, when two different hardened layers are formed to form a magnetic medium layer, in most cases the desired crystal orientation is not achieved, resulting in poor magnetic properties such as a worsening of the squareness ratio S* determined from the magnetization curve. (There was a problem with this.

This invention was made to solve the above-mentioned problems, and it has good crystal orientation, that is, magnetic properties, and CSS
The purpose is to obtain a highly reliable magnetic recording medium that can be used repeatedly.

[Means for solving problems]

The magnetic recording medium of the present invention has a nonmagnetic underlayer made of any one of yTiO2, TiCy, and TjN formed between the nonmagnetic hardened layer and the magnetic medium layer.

[Effect]

By forming the nonmagnetic underlayer made of any one of Ti02p TiC and TIN according to the present invention,
The adverse effects of the nonmagnetic hardened layer can be prevented, the crystal orientation of the magnetic medium layer can be improved, and the properties of hardness and good surface precision of the nonmagnetic hardened layer are not diminished.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (1) is an aluminum alloy substrate which is a non-magnetic substrate, (2) is a non-magnetic hardened layer, and (3) is a 'r1o2 non-magnetic lower non-magnetic underlayer and a magnetic medium layer.

This invention will be explained in more detail below with reference to specific examples, but the invention is not limited thereto.

EXAMPLE A disk-shaped aluminum alloy substrate (1) was coated with an alumite film having a thickness of 4 μm as a nonmagnetic hardened layer (2).

After mirror finishing the alumite film, non-magnetic underlayer (3)
A TlO2 film was formed by a reactive sputtering method. Furthermore, an r -Fe2O3 thin film was formed as a magnetic medium layer (4).

Samples with different TlO2 film thicknesses were prepared and two different measurements were performed, and the results are summarized in a table. Regarding crystal orientation,
Measured by line diffraction method, r-76203 (spinel type)
It is expressed by the ratio of the beak in the 222nd direction (222) and the beak in the 31st direction (31)). Squareness ratio S*
was determined from the magnetization curve.

Furthermore, FIG. 2 shows an example of the thickness of the non-magnetic underlayer and changes in each characteristic value when the non-magnetic underlayer is TlO2.

An example in which the nonmagnetic underlayer is made of Tic is shown in FIG. In the figure, curve 1) represents a change in I (222)/Equation (31)), curve 12 represents a change in S*, and curve 13 represents a change in the ratio of 088 times.

Note) C8 when TlO2 film thickness is 0 or not (not formed)
It was expressed as a ratio with the S number being 1.

As is clear from the table and FIG. 2, when the thickness of tTiO2 exceeds 50λ, the crystal orientation and the S* value improve. On the other hand, the film thickness of 'rlo2 is 240
When the number exceeded 0 and reached 30,001 or more, the number of CSSs worsened. If the film thickness of 'r1o2 is too thick, the effect of the non-magnetic hardened layer is weakened, which is thought to have led to the deterioration of the number of times (88 times. Often 300
More than 0 people is not desirable.

In the above embodiment, the case of a TiO2 film was explained, but similar results can be obtained even in the case of Tic or TIN, and the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a nonmagnetic substrate and a nonmagnetic hardened layer coated on the nonmagnetic substrate.

This nonmagnetic hardened layer is coated with a nonmagnetic underlayer made of any one of TiO2, TiC, and TiN, and the nonmagnetic underlayer is coated with a magnetic medium layer. Also, the magnetic properties are improved, the number of CEI8 times is increased, and a highly reliable magnetic recording medium can be obtained.

In addition, the thickness of the nonmagnetic underlayer made of any one of TlO2, Tic, and TIN is set to 50 to 24 mm.
If the number of people is within the range of 00 people, the above-mentioned effect will be further enhanced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a magnetic recording medium obtained by an embodiment of the present invention, and FIGS. 2 and 3 are characteristic diagrams showing changes in the thickness of the nonmagnetic underlayer and each characteristic value. be. +1) is a non-magnetic substrate, (2) is a non-magnetic hardened layer, (3) is a 'rlo2 non-magnetic lower non-magnetic underlayer and a magnetic medium layer,

Claims (2)

[Claims] (1) A nonmagnetic substrate, a nonmagnetic hardened layer coated on this nonmagnetic substrate, and a TiO_2 coated on this nonmagnetic hardened layer.
A magnetic recording medium comprising a nonmagnetic underlayer made of any one of , TiC, and TiN, and a magnetic medium layer coated on the nonmagnetic underlayer. (2) The thickness of the non-magnetic underlayer made of any one of TiO_2, TiC, and TiN is 50~2
2. The magnetic recording medium according to claim 1, wherein the magnetic recording medium has a thickness of 400 Å.