JPH0223511A - Thin metallic film type magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the thin metallic film type magnetic recording medium for high-density recording which is lowered in recording and reproducing noises as low as possible and has well balanced resolving power and noises and low peak shift by forming a magnetic metallic film having a specific compsn. on a nonmagnetic substrate. CONSTITUTION:The magnetic metallic film formed on the nonmagnetic substrate consisting of an aluminum alloy plate, etc., is the quaternary alloy having the compsn. expressed by Co1-x-y-zNixTaz (where x, y, z denote atomic ratios) formed by adding Ta to a CoNiCr. The weatherability of the magnetic film is poor when the atomic ratio (x) of the Ni in this compsn. is below 0.05. Conversely, the saturation magnetic flux density decreases and the good magnetic characteristics and electric characteristics are not obtainable if the ratio exceeds 0.25. The weatherability of the magnetic film is insufficient if the atomic ratio Y of the Cr is below 0.07 and the good magnetic characteristics and electric characteristics are not assured if the ratio exceeds 0.14. The sufficient effect of decreasing the magnetization transition width is assured by specifying the lower limit of the Ta to 0.01 and the degradation in the magnetic characteristics and electric characteristics is suppressed by specifying the upper limit to 0.03.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a metal thin film magnetic recording medium.

[Conventional technology]

So-called coated magnetic recording media, in which a magnetic film made of iron oxide powder and an organic binder is formed on the surface of a non-magnetic substrate, have traditionally been used as recording media in magnetic recording devices. Due to the demand for higher recording density, a shift is being made to metal thin film type magnetic recording media in which a ferromagnetic metal thin film is used as the magnetic film.

The component composition of the magnetic film formed on the nonmagnetic substrate is determined by comprehensively evaluating magnetic properties, recording/reproducing characteristics, weather resistance, etc., but generally Co, CoNi, CoCr, etc.
Alternatively, a CoNiCr alloy is used.

[Problem that the invention seeks to solve]

The metal thin film type magnetic recording medium allows for higher density recording than conventional coating type magnetic recording media, but it is difficult to expect higher densities due to the large recording and reproduction noise. In order to improve the recording density, it is necessary to reduce reproduction noise and reduce the peak shift of the reproduced waveform due to noise.

In view of the above, it is an object of the present invention to provide a metal thin film type magnetic recording medium for high-density recording with low peak shift and a good balance between resolution and noise by reducing recording and reproducing noise as much as possible.

[Means and effects for solving the problems] In the metal thin film magnetic recording medium of the present invention, the metal magnetic film is Co1-X-Y-ZN i xCr vT az [However, x, y, z indicates the atomic ratio, and X is 0.05 to 0.2
5, y is 0.07-0.14, Z is 0.01-0.03
It is characterized by having the composition shown below.

As described above, the metal-based magnetic film of the magnetic recording medium of the present invention is a quaternary alloy in which Ta is added to a CoNiCr-based alloy. CoNiCr-based ternary alloy is an alloy that has high coercive force (Hc) and high residual magnetic flux density (Br) that are desired as a magnetic film, and by adding an appropriate amount of Ta as a fourth element to it according to the present invention, CoNiCr A remarkable improvement in recording and reproducing noise characteristics can be obtained without impairing the magnetic properties and electrical properties of the ternary alloy magnetic film. This is due to the addition of an appropriate amount of Ta, which causes changes in the magnetocrystalline anisotropy of the magnetic film, refinement of crystal grains, grain boundary precipitation of Cr, etc. As a result, the magnetic domain becomes finer and more isolated, and the magnetic transition width increases. is expected to decrease.

In the present invention, in the composition of the CoNiCrTa alloy of the magnetic film, the atomic ratio (X) of Ni is set to 0.05 to 0.25.
The reason for this is that if it is less than 0.05, the weather resistance of the magnetic film will deteriorate, while if it exceeds 0.25, the saturation magnetic flux density (B
s) decreases, making it impossible to obtain good magnetic and electrical properties. In addition, the atomic ratio (Y) of Cr is 0.0
The reason why it is set to 7 to 0.14 is because if it is less than 0.07, the weather resistance of the magnetic film will be insufficient, and if it is more than 0.14, it will not be possible to ensure good magnetic and electrical properties.

Furthermore, regarding the amount of Ta, the lower limit of the atomic ratio was set to 0 and Ol in order to ensure a sufficient reduction effect on the magnetization transition width by Ta addition, and the upper limit was set to 0.03 because it This is because, even if added in excess of 50%, the above-mentioned effects will not increase, and on the contrary, the magnetic and electrical properties will deteriorate.

The metal thin film magnetic recording medium of the present invention includes magnetic disks, various magnetic drums, magnetic tapes, magnetic sheets, and the like. These are all except that their magnetic films are made of a CoNiCrTa-based quaternary alloy having the above composition.
It can be manufactured according to known general processes and conditions. For example, regarding a magnetic disk for in-plane recording, the substrate is made of an aluminum alloy plate, etc., and a hard N1-P plating film (film thickness: e.g. 15 to 25 μm) is provided on the surface by electroless plating, and the plating film surface is After the texture treatment, a Cr film having an appropriate thickness (for example, 500 to 3,000 thick) is formed as an underlayer for imparting in-plane anisotropy to the magnetic film. A CoNiCrTa based quaternary alloy magnetic film (film thickness, for example, 500 to 2000 layers) having the above composition is formed on the Cr film surface. Next, as a protective film to prevent wear and damage of the magnetic film, a film having lubricity and wear resistance, such as a carbonaceous film (thickness: e.g. 15
0 to 600 persons), a magnetic disk for longitudinal recording having a multilayer laminated structure is obtained.

Note that the laminated structure is not limited to the above example; for example,
Prior to forming the carbonaceous film on the magnetic film, about 10
By forming a Cr film with a thickness of 0 to 500 nm, the weather resistance of the magnetic disk can be further improved. Furthermore, in addition to forming a carbonaceous film on the magnetic film surface, a lubricant (film thickness: for example, 10 to 100) can be provided on the surface to improve the protective lubrication function for the magnetic head. .

Note that each layer can be formed by a sputtering method, an ion blating method, a vacuum evaporation method, or the like.

〔Example〕

CI) Production of test magnetic disk A N1-P electroless plating film (film thickness 20 μm) was formed on the surface of an aluminum alloy substrate (outer diameter 130 mm, inner diameter 40 mm, thickness 1.9 mm). , after polishing and texturing the surface, magnetron sputtering method (argon atmosphere pressure: 0.7 Xl0-2 torr)
), a Cr film (film thickness: 2,500 layers) was first formed, and then a magnetic film was formed using a CoNiCrTa based quaternary alloy as a target. The composition of the magnetic film is Co11,? O5
N t o, Ib5Cr o, ++T a o, oz
・The film thickness is 1000 people. Furthermore, a carbonaceous film having a thickness of 300 mm was formed as a protective film on the magnetic film surface to obtain a test magnetic disk 1 (130 [11111 type)].

Its coercive force (HC) is 11,000e, and the product of residual magnetic flux density and film thickness (Br·δ) is 500G·μ.

In addition, as a comparative example, a test magnetic disk 2 was obtained through the same process as above except that a CoNiCr-based ternary alloy was used as a target and an alloy magnetic film of Coo, yNio, and xcro was formed.

In order to properly compare the noise characteristics of the magnetic disks 1 and 2 under test, the Cr film and magnetic film of the magnetic disk 2 under test had the same Hc and Br as those of the magnetic disk 1 under test.
・The film was formed so that δ was obtained.

(n) Comparison test of noise characteristics Recording and reproduction (magnetic recording density: 19 KFCI) were performed using a thin film head for each test magnetic disk 1 and 2, and the peak shift (n
5ec) and noise characteristics using a spectrum analyzer.

(a) Measurement of peak shift in peak shift pit error rate IQ-10.

Test disks Peak shift (15ec) magnetic disk 1 (invention example) 12.0 magnetic disk 2 (comparative example) 14.5 (b) Noise characteristics Spectrum analyzer center frequency: 5 MHz, frequency span: 10 Mtlz.

Resolution: 30 KHz The measurement results for magnetic disk 1 (invention example) are shown in Figure 1, and those for magnetic disk 2 (comparative example) are shown in Figure 2.
A1 is the modulation noise when the recording frequency is 7.5 MH2,
At is the modulation noise at 5.01 vHlz, A is the modulation noise at 2.5 MHz, and B is the system noise.

As is clear from the above test results, the magnetic disk of the invention example has low noise, and the peak shift due to noise is greatly improved.

〔Effect of the invention〕

The magnetic recording medium of the present invention has excellent magnetic and electrical properties of the CoNLCra-based alloy magnetic film, as well as good noise characteristics superior to that of the ternary alloy magnetic film, and is resistant to peak shifts due to mutual interference of reproduced waveforms. The peak shift due to noise is significantly improved without any change, and therefore the −
This makes it possible to increase the density of magnetic recording media, make magnetic recording media more compact, and improve quality and performance.

[Brief explanation of the drawing]

FIGS. 1 and 2 are graphs showing background noise spectrum analysis during recording and reproduction of a magnetic disk. Figure 1

Claims (1)

[Claims] 1. In a magnetic recording medium in which a metal-based magnetic film is formed on a non-magnetic substrate, the metal-based magnetic film is Co_1_-_X_
-_Y_-_ZNi_XCr_YTa_Z [However, x,
y and z indicate the atomic ratio, x is 0.05 to 0.25, y is 0.07 to 0.14, and Z is 0.01 to 0.03]
A metal thin film magnetic recording medium with excellent noise characteristics, characterized by having a composition represented by: