JPS6126927A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent S/N and sensitivity by forming a lower soft magnetic layer and non-magnetic layer in this order on a base body then providing an upper soft magnetic layer which has the saturation magnetic flux density larger than the saturation magnetic flux density of the lower soft magnetic layer and of which the magnetic wall is made into Neel structure thereon and forming a vertically magnetizable film on said layer. CONSTITUTION:The lower soft magnetic layer 6 consisting of ''Permalloy(R)'', etc. is formed to about 4,000Angstrom on the base body 4 consisting of a polyimide film, etc. After the non-magnetic layer 8 consisting of SiO, TiO2, Al, Cn, Sn, etc. is formed thereon, the upper soft magnetic layer 7 constituted of the Neel magnetic wall made of either the same material as the material of the layer 6 or the different material having the saturation magnetic flux density larger than the saturation magnetic flud density of the layer 6 and <=0.1mu film thickness is formed thereon to provide the double soft magnetic layers 5. The vertically magnetizable film 9 consisting of Co-Cr, etc. is thereafter formed on the layer 7. The layer 7 absorbs the noise of the layer 8 to decrease the noise over the entire part. The magnetic recording medium having the good recording and reproducing sensitivity and improved S/N is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording medium suitable for high-density magnetic recording.

Conventional configurations and their problems In order to fully utilize the advantages of perpendicular magnetic recording and realize ultra-high density recording, it is necessary to improve the magnetic head and the dual-layer medium.

In particular, the establishment of mass production technology for dual-layer media is an urgent task for the practical application of perpendicular magnetic recording, but from the viewpoint of film formation speed, it is significant to establish a configuration that allows high-performance dual-layer media to be obtained using the vacuum evaporation method. deep.

As far as is known at present, the limits of recording ratio are only mentioned in terms of signal output, and noise is not covered, so there is a large gap with reality.

In particular, the soft magnetic layer requires a thickness of about 0.5 μm in order to improve recording sensitivity, so the noise is rather low from 0.1 μm to 0.
．． This becomes more problematic than a 2 μm perpendicularly magnetized film such as Co-Cr.
It has not been possible to obtain a sufficient signal-to-noise ratio (S/N).

OBJECTS OF THE INVENTION An object of the present invention is to provide a magnetic recording medium that can perform perpendicular magnetic recording with an excellent S/N ratio.

Structure of the Invention The magnetic recording medium of the present invention has a laminated structure of a soft magnetic layer and a perpendicular magnetization film, and the soft magnetic layer is divided into two with a nonmagnetic layer in between.
The upper layer has a Neel domain wall and has a higher saturation magnetic flux density than the lower layer, resulting in excellent S/N in high-density recording and reproduction.
'i can secure it.

Description of examples The present invention will be described below with reference to the drawings.

FIG. 1 is an enlarged cross-sectional view of a conventional magnetic recording medium. 1st
In the figure, 1 is a polymer substrate 2 is a soft magnetic layer such as permalloy, 3
is a perpendicular magnetization film such as Co--Cr.

In this configuration, for example, when comparing the permalloy film with and without a 0.6 μm film, under the same -Co-Cr film conditions, the recording sensitivity,
It is known that the reproduction sensitivity is improved by about 10 times, but the noise is large and the S/N is always about 42 dB higher than QdB.

The present invention was completed by analyzing the noise and determining that the cause was not the Co--Cr film but rather the soft magnetic layer, and an example of the structure is shown in FIG.

In FIG. 2, 4 is a non-magnetic substrate such as a polymer, 6 is a soft magnetic layer, and this soft magnetic layer is divided into a first soft magnetic layer 6 and a second soft magnetic layer 7, and a non-magnetic layer 8. Laminated through. 9 is a perpendicular magnetization film.

The nonmagnetic substrate used in the present invention is a disk-shaped substrate made of a polymer film such as polyethylene terephthalate or polyimide, or an aluminum alloy.

The perpendicular magnetization film used in the present invention is Co-Cr.

Co-0Co-Ti Co-Mo Co-W C
o-V Co-P, Co-Mn-P, Co-N
sputtering method with i-Cr, Co-Ni-0, etc.
It is formed by ion blating method, electron beam evaporation method, electroless plating method, etc., and is from 0.06 μm to 0.2 μm.
Measurements down to μm are often used.

The soft magnetic layer of the present invention includes a monomer represented by permalloy,
In addition, Ni-Fe-Mn, Ni-Fe-Zn, Nf-Fe
-Mo, etc. may be used, and the nonmagnetic layer may be M.

Cu, Ti, Mo, zr, Sn, Au, Ag, SnO2
, Sin.

Any of SzO2, TiO2, etc. may be used.

The first soft magnetic layer and the second soft magnetic layer may be made of the same material or different materials, but the domain wall of the second soft magnetic layer is a Neel domain wall and has a higher saturation magnetic flux density than the first soft magnetic layer. Otherwise, it must be abducted.

Although it cannot be determined unambiguously because it depends on the material and the film formation method, if the film thickness is 0.1 μm or less, it can be constructed almost entirely of Neel domain walls.

With this configuration, the spin rotation within the domain wall is in-plane, and the high saturation magnetic flux density of the second soft magnetic layer makes it possible to absorb the noise component of the first soft magnetic layer, resulting in an overall improvement It is thought that noise can be significantly improved, recording and reproduction sensitivity can be kept good, and S/N can be improved.

An example will be described in more detail below.

〔Example〕

Ni-Fe(
Ni 80wt%) film was deposited, then electron beam evaporated in Si f oxygen to form 5iOi, and again Ni-Fe
A film is formed, and Co-Cr (Cr20wt%
) films were electron beam evaporated.

1st. The saturation magnetic flux density of the second soft magnetic layer was adjusted using Ar pressure.

The surface temperature of the cylindrical cap during vapor deposition was determined by recording and reproducing with a throat and evaluating the S/Ni.Tape conditions and evaluation results are summarized in the table.0The main magnetic pole of the vertical head is G o -B non- Crystalline alloy with a width of 0.19μm
, ) The rack width was 9 μm for comparison.

(Left below) As is clear from the table above, the components of the present invention can achieve an S/N of 45 dB, which is generally necessary for the practical use of digital equipment, by recording ultra-high density recording with a recording wavelength of 0.3 μm and a rank width of 9 μm. It can also be obtained through reproduction, and is effective in the practical application of high-density magnetic recording, including miniaturization of equipment.

It has been confirmed that magnetic recording media with excellent S/''N can be obtained not only by magnetic disks but also by combinations of other materials in addition to magnetic tapes.

Effects of the Invention The magnetic recording medium of the present invention has a structure in which the soft magnetic layer is divided into two parts, the upper part has a Neel domain wall, and has a higher saturation magnetic flux density than the lower part, thereby improving S in non-direct magnetic recording and reproduction.
/N is an improved version, and its practical effects are significant.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a conventional magnetic recording medium, and FIG. 2 is an enlarged sectional view of a magnetic recording medium of the present invention. 4... Substrate, 6... First soft magnetic layer, 7
...Second soft magnetic layer (Nel domain wall structure) 8...
...Nonmagnetic layer, 9...Perpendicular magnetization film 0 Name of agent: Patent attorney Toshi Nakao, male, el or one person Figure 1 Figure 2

Claims (1)

[Claims] A magnetic recording medium characterized in that a soft magnetic layer is divided into two layers, the upper layer has a Neel structure, and a perpendicular magnetization film is disposed on the soft magnetic layer having a higher saturation magnetic flux density than the lower layer.