JPH0664730B2 - Magnetic recording body - Google Patents

Description

The present invention relates to a magnetic recording body used in a magnetic recording device.

(Prior Art) The improvement of the recording density of a magnetic recording device has been a constant trend in this field, and in recent years, a method capable of high-density recording in principle has replaced the conventional magnetic recording method using longitudinal (in-plane direction) magnetization. A magnetic recording method using perpendicular magnetization has been proposed.

In the magnetic recording medium used here, a soft magnetic film is formed on a single-layer medium and a substrate on which a perpendicular magnetic anisotropic film is formed directly on a substrate or via an underlayer, and then directly or via an underlayer. There is a so-called two-layer medium in which a perpendicular magnetic anisotropic film is formed.

(Problems to be solved by the invention) These magnetic recording materials include flexible recording materials using a plastic film as a substrate and NiP for Al alloy.
There are rigid recording bodies that use plated or alumite-coated substrates or hard substrates such as glass and ceramics. In recent years, particularly in rigid recording bodies, minute concentric concave and convex grooves (grooves) are formed on a disk substrate, and magnetic anisotropy of a magnetic film is imparted in the groove direction to improve magnetic characteristics and improve magnetic head and recording body. We are trying to prevent adsorption to the surface.

However, it consists of a soft magnetic film and a perpendicular magnetic anisotropic film.
When the layered medium is formed on a substrate having concentric and concavo-convex concaves and convexes, a magnetic anisotropy with the easy axis in the direction of the groove is generated in a soft magnetic film with a reduced magnetostriction that is usually used, and this two-layered medium As a result of recording and reproducing, there was a problem that the high frequency magnetic permeability of the soft magnetic film in the longitudinal direction of the track was lowered and the recording frequency characteristic was significantly deteriorated.

As a conventional example, as shown in FIGS. 3 (a) and 3 (b), an aluminum alloy substrate is plated with NiP on the disc substrate 1 to form a concavo-convex portion by polishing in the circumferential direction of the disc disc during mirror polishing. Formed a groove 2. The shape of this grooved structure may be a plastic substrate molded by a metal mold having an inclined unevenness as shown in FIG.

As this conventional example, an aluminum alloy substrate having a groove roughness (Ra) of 200Å was used, and a NiFe alloy (80 wt% Ni) was used as a target for the soft magnetic film to be formed by a sputtering apparatus. Internal stress of this time (sigma), the magnetic anisotropy constant of the magnetostriction constant (lambda) and the plane (Ku), respectively ^{+ 1 × 10 1 0 dyne /} cm 2, + 2
× 10 ^- a ^{6, 1 × 10 4 erg /} cc. In this case, magnetic anisotropy parallel to the streak direction occurred.

An object of the present invention is to solve such problems, to provide a magnetic recording body having improved high frequency characteristics and increased recording density.

(Means for Solving Problems) The magnetic recording medium of the present invention comprises a disk substrate having concavities and convexities with a groove roughness of 300 Å or less formed concentrically on the surface, and a Ni film formed on the surface of the disk substrate. A soft magnetic film made of a Fe-based alloy film and having a negative magnetostriction constant with internal stress of the film having a tensile stress, or having a positive magnetostriction constant of internal stress of the film having a compressive stress, and A perpendicular magnetic anisotropy film formed on the soft magnetic film.

(Operation) In the magnetic recording medium of the present invention, by causing the soft magnetic film to exhibit magnetic anisotropy having an easy axis perpendicular to the groove direction of the irregularities,
The frequency characteristics of the magnetic permeability of the soft magnetic film in the longitudinal direction of the recording track can be improved, and the recording / reproducing characteristics can be greatly improved.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 and 2 are partial cross-sectional views of the disk substrates of the first and second embodiments of the present invention.

In the substrate 1 of this embodiment, an aluminum alloy substrate was plated with NiP, and when the mirror-polishing process was performed, a third disc was formed in the circumferential direction of the disc disc.
As shown in FIGS. (A) and (b), a substrate on which irregularities are formed by polishing was used. The shape of this grooved structure has a similar effect even in a plastic substrate molded by a mold as shown in FIG.

As the disk substrate 1 of the first embodiment (FIG. 1), those having a groove roughness _Ra (average roughness) of 200Å and 300Å were used, and a substrate having a groove roughness of 500Å was used as a comparative example. . Recording bodies using these substrates are referred to as recording bodies I, II, and III, respectively.

A NiFe alloy (85 wt% Ni) was used for the preparation of the soft magnetic film, and 0.4 μm was formed by using a magnetron sputtering device.

FIG. 5 is a characteristic diagram showing the relationship between the internal pressure of the NiFe alloy film and the argon pressure P _Ar during formation. As shown
In the sputtering apparatus used in this embodiment, P _Ar ˜2 mTo
The stress changed to tensile stress (positive sign) and compressive stress (negative sign) at the boundary of rr, and the internal stress was controlled by changing the argon pressure. In this embodiment, P _Ar was performed sputtering in ～6MTorr, each 2 × 10 ^{1 0} The magnetostriction constant of the internal stress and the film of the film formed on each substrate dyne / cm ² and -15 × 10 ^{- 6}
Met.

Table 1 shows the results of measuring the in-plane anisotropy of the recording bodies I, II, and III on which the soft magnetic film was formed with a magnetic torque meter.

In the magnetic anisotropy constant Ku, a negative sign has an easy axis in the direction orthogonal to the groove direction, and a positive sign has an easy axis in parallel with the groove direction.

On the recording medium on which the soft magnetic film was formed, a CoCr film of 0.2 μm was formed by magnetron sputtering using a CoCr alloy (22 at% Cr) target at P _Ar / mTorr. Vertical coercive force of the formed film was 500O _e.

In the second view of the second embodiment, a substrate having a shape shown in FIG. 4 as the disk substrate, the roughness R _a of the groove 20
It was 0Å. NiFeCr alloy (Ni _{6
A 0} Fe _{3 0} Cr _{1 0} ) target was used to form 0.4 μm by using a magnetron sputtering apparatus. Sputtering pressure P _Ar
In 0.8MTor, internal stress compression pressure ^{-1.9 × 10 1 0 dyne / cm} 2 of the soft magnetic film at this time (NiFeCr), the magnetostriction constant is + 20 × 10 ^- it was ^6.

Table 1 shows the results of measuring the in-plane anisotropy of the recording body V on which the soft magnetic film was formed with a magnetic torque meter. The magnetic anisotropy constant Ku was −1.5 × 10 ⁴ erg / cc, and anisotropy occurred at right angles to the mizo direction.

After forming this soft magnetic film, a CoCr film was formed to a thickness of 0.2 μm using the same CoCr alloy target as in the first embodiment. Vertical coercive force of the film was 550O _e.

Using the recording bodies I to V of these Examples, Comparative and Conventional Examples,
Recording / reproduction was performed with a thin-film type main pole excitation magnetic head having a return path, and the recording density characteristics were investigated. The thickness of the main magnetic pole is 0.3 μm.

It showed D _{5 0} representing the respective recording densities in Table 2 _(density at the output of the half arc Tatsunami output).

From this table, the recording material I of the present embodiment, II, recording density D _{5 0} of V
Of 90,75,80K-BPI, respectively, and sufficiently high density characteristics were obtained. On the other hand, in the recording bodies III and IV of the comparative example and the conventional example, D
_{5 0} respectively inferior embodiment in 50,60K-BPI.

(Effects of the Invention) As described above, according to the present invention, it is possible to obtain a magnetic recording body having a high recording density.

[Brief description of drawings]

1 and 2 are partial cross-sectional views of the first and second embodiments of the present invention, FIGS. 3 (a) and 3 (b) are plan views and partial cross-sectional views of the disk substrate, and FIG. FIG. 5 is a partial cross-sectional view of a disk substrate manufactured by using a mold, and FIG. 5 is a characteristic diagram showing the relationship between the sputtering pressure and the internal stress of the film when the NiFe alloy film is formed. 1 ... disk substrate, 2 ... groove, 3 ... substrate cross section, 4
…… Substrate cross-sectional shape, 5 …… Substrate, 6 …… NiFe film, 7 ……
CoCr film, 9 ... NiFeCr film.

Claims (1)

[Claims] 1. A disc substrate having concentric concavities and convexities with a groove roughness of 300 Å or less formed on the surface thereof, and a Ni--Fe alloy film formed on the surface of the disc substrate and having a negative magnetostriction constant. And the perpendicular magnetic anisotropy formed on the soft magnetic film, and the internal stress of the film has tensile stress or the magnetostriction constant is positive and the internal stress of the film has compressive stress. A magnetic recording medium comprising a film.