JPS61129726A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide an isotropic magnetic characteristic to a magnetic recording medium without providing magnetic anisotropy within the magnetic recording medium and to reduce reproduced output modulation by constituting a horizontally magnetizable film layer of a high-speed magnetic permeability material composed of the compsn. contg. nickel and other metallic components and making the content of nickel larger than the content thereof when magnetorestriction is zero. CONSTITUTION:The horizontally magnetizable film layer consists of the compsn. contg. nickel and other metallic components and the content of nickel is made more than the content thereof when the magnetorestriction is zero. The magnetic anisotropy in the direction of a width w1 and longitudinal direction (a) is eliminated in the anisotropic magnetic field dHk=0 (Oe) and the isotropic magnetic characteristic is obtd. The content of Ni is therefore so selected that the isotropic magnetic characteristic of the anisotropic magnetic field Hk=0 (Oe) is obtd. Such content of Ni is 80-82wt% when the horizontally magnetizable film layer is formed of 'Ni-FeMo Supermalloy(R)' and is 81-83wt% when said layer is formed on 'Ni-Fe Permally(R)'.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a magnetic recording medium for perpendicular magnetic recording.

The conventional perpendicular magnetic recording method can achieve a recording density of about 10 to 100 times higher than the conventional longitudinal magnetic recording method, and is attracting attention as a high-density magnetic recording method. As a magnetic recording medium for perpendicular magnetic recording, for example, as shown in FIG. A two-layer film structure in which a perpendicular magnetization film layer 3 serving as a magnetic recording Q layer is laminated thereon is known. The horizontal magnetic film layer 2 is made of Ni-F.
The perpendicular magnetic film layer 3 is made of e-Mo supermalloy or Ni-Fe permalloy, and the perpendicular magnetic film layer 3 has a composition of Co-Cr.

When performing magnetic recording in the magnetic recording medium with the above-mentioned two-layer film structure, for example, as shown in FIG. When the auxiliary magnetic pole 5 is arranged at layer 3
is perpendicularly magnetized. Therefore, in a magnetic recording medium having a two-layer film structure, high-density magnetic recording can be performed in an equivalent state in which the auxiliary magnetic pole 5 is brought very close to the perpendicularly magnetized film layer 3. Furthermore, due to the presence of the horizontal magnetization film layer 2, a horseshoe-shaped magnetization mode is formed with respect to the perpendicular magnetization of the perpendicular magnetization film layer 3, and the demagnetization effect is reduced, without impairing recording density characteristics.
Advantages such as the ability to improve the sensitivity of recording and reproduction in the vertical direction by more than 10 times and the ability to improve the storage stability of recording are also obtained.

A sputtering method is employed as an industrial method for manufacturing the above-mentioned magnetic recording medium for perpendicular magnetic recording. FIG. 3 is a diagram schematically showing a magnetoconsbater type manufacturing apparatus. In the figure, 7 is a vacuum chamber into which A gas, etc. is introduced and the pressure is set to about 10 Tarr, 8 is a target, and 9 is a magnet placed on the back side of this target 8.1
0 is a non-magnetic substrate running in the direction of arrow a, 11 is a supply roll that supplies the non-magnetic substrate 10, 12 is a take-up roll, 13
is a cooling drum.

When forming the horizontal magnetization film layer 2, the target 8 is made of Ni-Fe-0-based supermalloy or Ni-Fe.
The perpendicular magnetization film layer 3 is made of a Go-Cr based material. Also,
As shown in FIG. 4, the target 8 is a non-magnetic substrate 10.
It is formed into a rectangular shape having a width W2 that can cover the width W1 of
1 and a magnet 9 having a core 92.

In the above device, when a high voltage of 400 to 500 V is applied between the cooling drum 13 and the target 8 with the target 8 side being negative, plasma discharge is generated in the vacuum chamber 7 and Ar is applied to the negative side of the target 8. It collides with the target surface due to the electric potential, and metal atoms on the target surface are knocked out. The ejected metal atoms are deposited on the surface of the nonmagnetic substrate 10 facing the target 8. As shown in FIG.
Depending on the shape of the magnet 9 placed on the back surface of the target 8, it has a rectangular ring shape.

Disadvantages of the Prior Art Conventionally, in order to improve magnetic recording characteristics, the horizontally magnetized H'J layer 2 has been formed with a composition such that the magnetostriction is zero. For example, when the horizontal magnetization film layer 2 is formed of Ni-Fe-Ma supermalloy, the old composition is 79 wt%.
In the case of Ni-Fe-based permalloy, the content is set to 80 wt%.

However, when a horizontally magnetized film layer with a composition of zero magnetostriction is formed by sputtering, magnetic anisotropy occurs in which magnetization is difficult in the length direction (running direction a) of the nonmagnetic substrate IO and magnetization is easy in the width direction W1. (See FIG. 4), it has been found that a problem arises in that the modulation of the playback output becomes large. This is a reproduction output characteristic diagram obtained by tracing a circular magnetic disk (floppy disk) obtained by punching a magnetic recording medium obtained by the seventh sputtering method into a circular shape over a 380° circumference. be. As shown in FIG. 7, clear reproduction output modulation can be seen in the composition of zero magnetostriction. The reproduction output modulation appears to be large in the direction of difficult magnetization a and small in the direction of easy magnetization W1.

Such magnetic anisotropy is caused by the fact that when a magnetized film layer is formed by sputtering, metal atoms are ejected in a rectangular ring shape according to the shape of the magnet 9, as shown in FIG. 0, which is caused by precipitation along the width W1 of the non-magnetic substrate 10, for example,
To explain more specifically using a circular magnetic recording medium as an example, as shown in FIG. 5, when a magnetic disk 15 is manufactured by punching a circular magnetic recording medium 14 obtained by a sputtering method, This magnetic disk 15 is
The traveling direction aL of the magnetic recording medium 14 -, (shi(i)
-]--su old g-+i r# 11 side ν day a 斡, roux -1st 1 heavy weight ℃1 bite
Magnetization is facilitated in the diametrical direction that coincides with the n) direction. Therefore, reproduction output modulation as shown in FIG. 7 occurs.

Purpose of the Invention The present invention solves the above-mentioned conventional problems, and provides a magnetic recording medium for perpendicular magnetic recording that has no magnetic anisotropy within the magnetic recording plane, has isotropic magnetic properties, and has small reproduction output modulation. The purpose is to provide recording media.

Structure of the Invention In order to achieve the above object, the present invention provides a magnetic recording medium in which a horizontal magnetization film layer and a perpendicular magnetization film layer are sequentially laminated on the surface of a non-magnetic substrate, in which the horizontal magnetization film layer is made of nickel. It has a composition containing other metal components, and is characterized in that the content of nickel is greater than the content when magnetostriction is zero.

FIG. 6 is a characteristic diagram showing the relationship between Ni content and magnetic field. In the figure, the horizontal axis represents the Ni content (wt%), and the vertical axis represents the anisotropic magnetic field Hk (Oe). A is the characteristic of the supermalloy horizontally magnetized film layer, and B is the characteristic of the permalloy horizontally magnetized film layer. Anisotropic magnetic field Hk = O(
Oe) A positive direction is a direction in which magnetization is easy in the width direction of the nonmagnetic substrate 10 when forming a horizontally magnetized film layer by sputtering, a negative direction is a length direction,
In other words, the traveling direction a is a direction in which magnetization is easy. In the anisotropic magnetic field Hk = 0 (Oe), the magnetic anisotropy in the width w1 direction and the length direction & is eliminated, and isotropic magnetic properties are obtained.6 In the present invention, we focus on this property, Ni
The content of is selected so as to obtain isotropic magnetic properties with an anisotropic magnetic field Hk = 0 (Oe). The Xi content that provides such isotropic magnetic properties is equivalent to Xl-FI! for the horizontally magnetized film layer. When it is formed from -Mo-based supermalloy, it is 80 to 82 wt%, and when it is formed from Ni-Fe-based permalloy, it is 81 to 83 wt%.

FIG. 8 is a reproduction output characteristic diagram of the circular magnetic disk according to the present invention, in which almost no modulation is seen.

Effects of the Invention As described above, the present invention provides a magnetic recording medium in which a horizontal magnetization film layer and a perpendicular magnetization film layer are sequentially laminated on the surface of a non-magnetic substrate, in which the horizontal magnetization film layer is made of nickel. It has a composition containing other metal components, and is characterized in that the content of nickel is greater than the content when magnetostriction is zero,
It is possible to provide a magnetic recording medium for perpendicular magnetic recording that has no magnetic anisotropy within the magnetic recording plane, has isotropic magnetic properties, and has extremely small modulation.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the structure of a magnetic recording medium for perpendicular magnetic recording, Figure 2 is a diagram also showing the magnetic recording method, and Figure 3 is a diagram showing the structure of the magnetic recording medium shown in Figures 1 and 2. Figure 7fJ4 is a diagram schematically showing the configuration of a sputtering apparatus, and Figure 7FJ4 is a diagram showing the relationship between the target, nonmagnetic substrate, and magnet in the sputtering apparatus. Figure 5 explains the directions of easy and difficult magnetization in a circular magnetic disk. Figure 6 is a characteristic diagram showing the relationship between 1 content and magnetization, Figure 7 is a reproduction output characteristic diagram of a conventional magnetic recording medium, and Figure 8 is a reproduction output of a la% recording medium according to the present invention. It is a characteristic diagram. 1...Nonmagnetic substrate 2...Horizontal magnetic film layer 3...φ
Perpendicular magnetization film layer Fig. 1 Fig. 4 ■ C a) 2 Mudan station Fig. 5 Fig. 7 Fig. 8

Claims (3)

[Claims] (1) In a magnetic recording medium in which a horizontal magnetic film layer and a perpendicular magnetic film layer are sequentially laminated on the surface of a nonmagnetic substrate, the horizontal magnetic film layer has a high magnetic permeability composition containing nickel and other metal components. 1. A magnetic recording medium, characterized in that the nickel content is greater than the content when magnetostriction is zero. (2) The horizontal magnetization film layer has a composition of nickel, iron, and molybdenum, and the nickel content is 80 to 82 wt%.
A magnetic recording medium according to claim 1, characterized in that: (3) The magnetic recording medium according to claim 1, wherein the horizontal magnetic film layer has a composition of nickel and iron, and the nickel content is 81 to 83 wt%.