JPS6180521A - Vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To realize a recording medium capable of obtaining a high reproduction output by specifying the composition and the values of magnetic characteristics of a vertical anisotropic hard magnetic film of a magnetic recording medium. CONSTITUTION:The tape-system vertical magnetic recording medium is constituted of a soft magnetic film (b) on a nonmagnetic substrate (a) and a vertical anisotropic hard magnetic film (c) of Co-Ni-O on the film (b). The magnetic film (c) has the composition (Co1-xNiix)1-yOy (where 0<=x<=0.3 and 0.1<=y<=0.35), and is allowed to satisfy the coercive force HCLrt. angle>=300 Oe and the hysteresis squareness ratio Mrert. angle/Ms>=0.9. Besides, the variation in the oxygen composition in this case is regulated within + or -0.05, and the particle diameter is regulated to >=50Angstrom . Consequently, a recording medium capable of obtaining a high reproduction output can be obtained.

Description

[Detailed description of the invention]
1. The present invention relates to a perpendicular magnetic recording medium suitable for recording using a perpendicular head, which includes a so-called two-layer perpendicular recording medium in which a soft magnetic film and a perpendicularly anisotropic hard magnetic film are laminated.

(Prior Art) Recently, perpendicular magnetic recording has been attracting attention and research as a new magnetic recording method capable of high-density recording. The magnetic heads used in this system are considered to be perpendicular heads (single magnetic pole heads) and ring heads, and the medium is two-layer perpendicular recording with m layers of a stiff magnetic film and a perpendicularly anisotropic hard magnetic film. The medium is being considered.

Conventionally, perpendicular magnetization films used for perpendicular magnetic recording include Ku,
≧2πMs2 or Hah/Ha, ≧1 + BrL/B
It has been necessary to have the magnetic property of r p ≧ 1, but recently, 2
When recording on a layered perpendicular recording medium using a perpendicular head, the trick is that the reproduction output does not depend on the above characteristics, but depends on the squareness ratio of the hysteresis curve after correction of the parent magnetic field, Mr*/Ms and Hci. Understood, Mr.? /M8 and HO
Attempts have been made to obtain a two-layer perpendicular recording medium type perpendicular magnetic recording medium using a Co-0r film made of gold.

(Problems to be Solved by the Invention) However, in the conventionally proposed two-layer media type perpendicular magnetic recording body using the above-mentioned Co-Or film, when an Oo-Or film is created by a vapor deposition method, the Oo and Or Composition control is difficult due to the difference in vapor pressure, and in order to obtain an ○o-Or film with high vertical anisotropy, it is necessary to heat the substrate to a high temperature, so a room temperature substrate has a high vertical anisotropy. In addition, perpendicular anisotropy is difficult to obtain due to the degree of crystal orientation of the (-Malloy film) used as a soft magnetic film. As a result, there are problems such as the need for a base layer of Ti11 or the like, and with the two-layer medium used for the Co-0r film that has been used in the past, this has caused practical problems, especially when manufactured by the vapor deposition method.

On the other hand, the inventor previously reported that Co-0,0o-N was produced as a practical perpendicularly anisotropic hard magnetic film using a vapor deposition method on a room-temperature base material.
Various inventions related to i-0,0o-Ni-IFe-0 based vapor deposited films have been presented.

(Means for Solving All Problems) The present invention avoids the above-mentioned disadvantages of using the conventional Co-(! We investigated the application to a two-layer perpendicular magnetic recording medium, and provided a practical perpendicular magnetic recording medium TL, which consists of a soft magnetic film and a perpendicular anisotropic hard magnetic film on a non-magnetic base material surface. In a perpendicular magnetic recording body equipped with a 2NI perpendicular recording medium, this perpendicular anisotropic hard magnetic film has a composition (Oo, --Ni, )s-yOy (where O≦x≦
0.3, 0.10≦y≦0.35), Ha engineering≧50006* M rh 7M B2O,9 (M in i
r2 indicates the value of residual magnetization when corrected using the effective demagnetizing field coefficient obtained from H=Ho/Mr. Oxygen composition in the thickness direction region between the surface and the interface is 0
．． The variation Δ of y is within 0.05, and the average minor axis grain size of the columnar composition crystal grains is 50A or more.

For strings, Mr:7M8 indicates the squareness of the hysteresis curve corrected using the effective demagnetizing field coefficient. (Refer to Proceedings of the National Conference of the Communications Society of Japan, 1-209F) (Embodiments) Next, embodiments of the present invention will be described based on the accompanying drawings. FIG. 1 shows a tape-type live direct magnetic recording medium as an example of the present invention, in which a shows a non-magnetic base material made of a polyester film having a thickness of 4 and 12 μm, and b shows a film having a thickness of 5,000 μm deposited on the upper surface of the non-magnetic base material.
A is a soft magnetic film made of a malloy film or the like;
Qo-Ni-0 vertical anisotropic hard magnetic film. The 0o
-Ni-0 perpendicular anisotropic hard magnetic film C has a 0o-Ni-0 film having a y-value of 50. That is, it is known that the vertical anisotropy increases up to 50 at%. In addition, as a general vertical arsenic film, a film with large vertical anisotropy: 1, etc., squareness ratio h
Although it is thought that ir/Ms and coercive force HCL can be obtained with great clarity, as a result of many experimental studies, Co-Ni-0
The film is unique, and it is true that the Ha value increases when the oxygen composition reaches around yw50at%, but when Mr: 7M
A value of 8 means that the oxygen composition is 3+-0.55 or more, i.e. 35
It was found that the higher the hm elemental composition at at% or higher, the lower it becomes.

This is a phenomenon unique to the 0O-Ni-0 film. This is understood to be because when the oxygen composition in the film increases too much, the 00 grains become extremely fine, and a portion of the superparamagnetic grains begin to coexist. When this relationship was quantitatively studied, it was found that the average particle diameter of the 0O-N1 columnar particles in the minor axis direction should be at least soX. Therefore, in order to maintain the particle size of Oo-Ni particles of 2soK or more, the oxygen composition in the film needs to be y≦0.35 or less, that is, 55&t% or less. Therefore, 0o-N
If the average particle diameter of i particles is set to be 50x or more, M
It was found that the value of rL/Mli was maintained at 0.90 or more, and excellent recording and reproducing characteristics were obtained. Moreover, many test studies have shown that the oxygen composition in the film is y≧0.10, that is, 10at
% or less, it was found that high playback output could not be obtained. This is because the 0O-Ni ferromagnetic particles cannot be sufficiently isolated by the non-ferromagnetic oxide (Coo-N1p), the perpendicular anisotropy decreases, and the values of Mrb/Ms and Ha
This is because it is too powerful. The average particle diameter of the columnar Oo-Ni particles with Oat% of 10at% was 500A. From the above results, it was found that high reproduction output can be obtained when the oxygen composition value is in the range of 0.10≦y≦0.35. On the other hand, Co-N
Considering the composition ratio of Oo and N1 in the i-0 film,
As a result of many tests and studies, it was found that the N1 component in the 0o-Ni composition needs to be 30 at% or less. That is, 0o-Ni
In the -0 perpendicular magnetic film, the precipitated magnetic particles must be Hcp, but if it exceeds 50&t%, the FOO phase will be mixed, and the value of Mr/Ma will be less than 0.9-. This is because.

In this way, the oxygen composition in the 0o-Ni-0@perpendicular magnetic film must be in the range of 0.10≦y≦0.35, but the variation in the oxygen composition in the film thickness direction is large. It has been found that too much may have an adverse effect on the squareness ratio M r: /MB.

After considering this point, we found that the squareness ratio M rh /MS was 0.
To ensure 9 or more, the variation of y of the oxygen composition should be ±0.
It is found that it is necessary for the variation to be within 0.05. In other words, if the variation is ±0.05 or more, the columnar grain structure is disturbed;
It was found that the Mrz /Ms value was 0.9 or less. The variation in y of the oxygen composition in the thickness direction of the film, excluding the oxide layer formed on the surface and interface, is kept within the range of ±0.05.

In that case, the thickness of the oxide layer formed on the back surface and the interface was several tens to several hundreds of layers. Oxygen composition y in the film thickness direction
Keep the fluctuation within ±0.05! 0o-Ni
It is preferable to keep the oxygen partial pressure constant during the vapor deposition, and if this method is produced using the evaporation chamber separation type apparatus shown in the second figure, the desired perpendicular magnetic recording body with a large reproduction output can be obtained.

The device shown in the second figure is described in detail in the earlier application and will not be described in detail. That is, the inside of the vacuum processing chamber (1) is divided by the partition wall (2) into a vacuum evaporation chamber M (1 &) including an oxygen introduction pipe T31 and a metal material evaporation chamber (1b), and each of the seven chambers (1 &) (1b) are each connected to a vacuum pump via an exhaust control valve +41 (51) so that each can be independently exhausted, and the amount of oxygen supplied in the deposition chamber (1a) can be maintained at a constant rate. (6) is an electron beam gun, (7) is a container containing evaporation material a'2 (
8) is a pair of winding and winding rolls, (9) is the water-cooled can, and can (9) is between the rolls (8).
The glass tape base material b2 having the soft magnetic film & is passed over the surface of the river. The vacuum deposition chamber (1a) has a partition wall (101) at its upper part, and an upper section of the chamber (1C).
), and an exhaust control valve C12 is installed at the upper end of the chamber (1C).
It was connected to a vacuum pump through 1 to purify the inside of chamber 7 (1C).

Next, the structure f@Jt of the uninvented magnetic recording medium will be explained.

5oo on the top surface of smooth polyester film tape
A permalloy film 5000A having an oX thickness is formed by a conventional method. The Ha of this film was 50eX and the maximum magnetic permeability was 500. A 0o-Ni-0 perpendicularly anisotropic hard magnetic film having a moderate composition was formed on the surface of this film.

The film thickness was kept constant at zoaoX. The apparatus shown in the second figure was used to form this magnetic film. That is, the above 50
The tape (8) provided with a permalloy film having a thickness of 00λ was loaded into the vacuum processing chamber as shown in the figure, and transferred at a constant speed to 10,000 yen.

1 each of Co-10, 20, 30, 40 at% N1 alloys
! : Prepare each as an evaporation material and evaporate each as an evaporation source, 1lli! 02 gas was introduced from the /element introduction tube (31) and vertical evaporation was performed under the supply of a certain amount of oxygen according to the production of media with various oxygen compositions.At this time, the ultimate vacuum of the vacuum evaporation chamber (1a) The degree is I x 10-'Torr
The amount of oxygen introduced was maintained at 10 to 40 cc/mm.

The tape running speed was constant at 11 KW and the electron beam output was constant at 7 KW.

In this way, two magnetic films, a perpendicularly anisotropic hard magnetic film and a permalloy film having different compositions, were obtained on the winding roll.
Other magnetic recording bodies with metal layers were obtained. This recording tape was slit to a width of 50% inch and an auxiliary magnetic pole excitation type vertical head was used for recording and reproduction. The thickness of the main magnetic pole is 0.3 μm. With the recording density kept constant at 50 KBP, the optimum current was determined and recorded for each medium, and the reproduction outputs were compared.

The results for Oo, -, Oy thread membranes are shown in the 6th F;! ! Ja,
Shown in b and c. From this, it can be seen that high reproduction output can be obtained in the range of y from 0.1 to 0.55. Hot at that time
The value of 1j300008 or more, Mr, /Ma 'd
It is 0.9 or more. The value of H+1 increases until y increases to 0.5, but the value of Mr:/M8 +-! It decreases when y is 0.35 or more. This is because the particle size is less than 50A,
This is thought to be due to the presence of superparamagnetic particles. The particle size is from the lower limit of y of 0.1 to a particle size of 5ooX].

Similar results for Co--Ni-0 based films are shown in FIGS. 4 and 5. In the area surrounded by diagonal lines in the figure, there is a high playback output and an iAr of 0.9 or more:/! As value and 3000s
It can be seen that the above HCl value can be obtained.

FIG. 7 shows the results of measuring Mrb/MS k by changing the grain size by completely changing the precipitation rate when creating a film of 00°6500.115. It can be seen that the value of Mr,''/Ms rapidly decreases to 0.9 or less when the particle size is 50X or less.

Figures 8 and 9 show the variation Δy of oxygen composition y and Mrj/M.
Indicates the relationship with s. That is, FIG. 8 shows "0-7" as an example.
I Oo, 25 films (31 = 0.25) When i was created, the variation △y of the oxidation composition in the region in the film thickness direction, excluding the surface layer and the back surface Rtl-, was determined by Ouch analysis, and the results are shown in full. The results determined for the relationship with Mr:/Ms are shown in FIG. As is clear from this, △y is ±0.
When the value exceeds 05, the squareness ratio deteriorates rapidly. In this way, due to particle size and oxygen fluctuations, the squareness ratio Mr
It was found that ↓/Ms is greatly affected, and in order to obtain a film Mr2/M a value of 0.9 or more, the grain size must be 50 or more, and the variation in y of the inner layer in the film thickness direction is sufficient. ±0.
Must be within 05. The above excellent results were also obtained by sputtering and ion plating.

(Effect of the invention) In this way, due to the uninvention, the perpendicular anisotropic hard magnetic film k (OO+
-zNi:I:)1-3103' (However, 0≦x≦0.
6゜0.10≦y≦0.35), HCh
≧3000e.

yielding magnetic properties with M rL/Ms≧0.9;
Obtained in a perpendicular magnetic recording medium that provides high reproduction output, the variation of the predetermined value of the dielectric composition y in the thickness direction within the film is ±0.0.
5 or less and those with heel grain size soX or more are HQL≧30
00s, Mr,''/Ms≧0.9 can be completely ensured, and even with room temperature vapor deposition, a perpendicular magnetic recording body with high reproduction output can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a part of an example of an embodiment of the present invention, FIG. 2 is a cross-sectional side view of a guest equipment manufactured using the perpendicular magnetic recording T-film of the present invention, and FIGS. 5 a, b, c is the perpendicularly anisotropic hard magnetic film (Co"yoy) CD oxygen composition. Characteristic curves of the relationship between the perpendicularly anisotropic hard magnetic film (Co"yoy) CD and reproduction output, coercive force squareness ratio, and magnetic particle size are shown in Figures 4 to 6. , characteristic curves of the relationship between the oxygen composition, reproduction output, squareness ratio, and coercive force of the perpendicularly anisotropic hard magnetic film 0o-Ni-0, respectively. Kaida curve of type ratio, Figure 8 'l'X o
oo-? FIG. 9 shows a graph showing the relationship between the variation Δy of the oxygen composition and the squareness ratio at various points σ in the thickness direction of the fl O-25 film. a...Nonmagnetic base material b...Soft magnetic film C...Perpendicular anisotropic hard magnetic film Outside 2 people Fig. 1 Fig. 2 Fig. 3 Y (Cot -y Oy) Figure 4C. Q (at'/6) Endogenous output (50KBPI') Figure 5C. O(at'/J square ratio - 4° procedural correction ratio (method) Showa ■, 2nd and 7th

Claims (1)

[Claims] In a perpendicular magnetic recording medium comprising a two-layer perpendicular recording medium consisting of a soft magnetic film and a perpendicularly anisotropic hard magnetic film on a non-magnetic base material surface, the perpendicularly anisotropic hard magnetic film has a composition ( C
o_1-_xNi_x)_1_-_yO_y(However, 0≦
x≦0.3, 0.10≦y≦0.35), H
c＿■≧300Oe, Mr＿■＾*/Ms≧0.9(■
Mr_■^* indicates the value of residual magnetization when corrected using the effective demagnetizing field coefficient obtained from N=Hc/Mr), and the perpendicular anisotropic hard magnetization The variation Δy of the oxygen composition Oy in the region in the thickness direction existing between the surface and the interface of the film is within ±0.05,
A perpendicular magnetic recording body characterized in that the average minor axis grain size of the columnar crystal grains is 50 Å or more.