JP2544205B2 - Metal thin film magnetic recording medium for in-plane magnetization recording - Google Patents

Description

The present invention relates to a metal thin film magnetic recording medium having excellent noise characteristics, and more particularly to a magnetic recording medium for in-plane magnetization recording for performing magnetization recording in a direction parallel to the magnetic film surface. Regarding

[Conventional technology]

Recently, as a recording medium of a magnetic recording device, a metal thin film type magnetic recording medium in which a magnetic film on a non-magnetic substrate is a ferromagnetic metal thin film is placed on a conventional so-called coating type magnetic recording medium due to its high density recording property. It is changing. The component composition of the ferromagnetic metal thin film formed on the non-magnetic substrate is determined by comprehensively evaluating magnetic properties, recording / reproducing characteristics, weather resistance, etc., and is generally Co, CoNi-based, CoCr-based, or CoNiCr alloy is used.

The magnetic recording methods include a perpendicular magnetization recording method that utilizes magnetization in the film thickness direction of a magnetic film (magnetic recording layer) and an in-plane magnetization recording method that performs magnetization recording in a direction parallel to the magnetic film surface. The in-plane magnetization recording method has been technically preceded in connection with the fact that the flying magnetic head technology has been completed.

In a magnetic recording medium with in-plane magnetization, it is necessary to introduce magnetic anisotropy in which the easy axis of magnetization is oriented in the in-plane direction of the magnetic film. As a means for this, a Cr film is formed on a non-magnetic substrate. Then, a magnetic film is laminated on the film surface. Cr (body-centered cubic structure) crystal lattice (11
0) One side of face (A is the lattice constant) and the lattice constant c of Co (closest hexagonal structure), which is the main element of the magnetic film, are substantially equal, and the Co-based alloy magnetic film is epitaxially grown on the Cr film surface to form a layered interface. This is because the conformity is good and the magnetic anisotropy in which the c-axis is oriented in the in-plane direction is introduced into the magnetic film.

[Problems to be Solved by the Invention]

The present invention relates to a magnetic recording medium for in-plane magnetization recording using a Co--Cr magnetic film as a magnetic recording medium, in which noise characteristics for enabling high density recording can be obtained without impairing the excellent magnetic characteristics of the magnetic film. The present invention seeks to provide an improved magnetic recording medium.

[Means and Actions for Solving the Problems]

The present invention provides a magnetic recording medium for in-plane magnetization recording in which a metallic magnetic film is formed on a non-magnetic substrate via a Cr film, the magnetic film being made of a CoCrNb-based alloy represented by the following formula [I]. It is characterized by that.

Co _1-XZ Cr _X Nb _Z [I] In the formula, x and z represent composition ratios, x is 0.07 to 0.15, and z is
It is 0.01 to 0.10.

The metal-based magnetic film of the magnetic recording medium of the present invention is based on the CoCr-based alloy as described above, and has a component structure in which Nb is added thereto. The CoCr alloy is an alloy having a high coercive force (Hc) and a high residual magnetic flux density (Br), and by adding an appropriate amount of Nb to the alloy according to the present invention, its magnetic characteristics and electric characteristics are not deteriorated. In addition, a remarkable improvement effect of the recording / reproducing noise characteristic can be obtained. This is because the crystal magnetic anisotropy of the magnetic film changes with the addition of an appropriate amount of Nb, the crystal grains become finer,
Cr grain boundary thickening occurs, resulting in finer magnetic domains.
It is considered that this is due to isolation and a decrease in the width of the magnetization transition.

In the present invention, the Cr content (x) of the alloy composition of the magnetic film is set to 0.07 to 0.15. When the Cr content is less than 0.07, the weather resistance of the magnetic film is insufficient, and when it is more than 0.15, good magnetic properties and electric properties are obtained. This is because the characteristics cannot be secured.

Furthermore, the lower limit of the amount of Nb (z) is set to 0.01 in order to secure a sufficient effect of reducing the magnetization transition width by the addition of Nb described above, while the upper limit of 0.10 exceeds that. This is because not only the effect is saturated, but also the magnetic characteristics and electrical characteristics are deteriorated. In addition,
The effect of improving the noise characteristics by the addition of Nb requires the coexistence of Cr, and cannot be obtained in a Co system containing no Cr. Therefore, in the present invention, the CoCr type base alloy is used.

The metal thin film type magnetic recording medium of the present invention includes a magnetic disk, a magnetic drum, a magnetic tape, a magnetic sheet and the like. Any of these can be manufactured according to known steps and conditions except that the magnetic film is made of a CoCrNb-based alloy having the composition represented by the above formula [I]. For example, in the case of a magnetic disk for in-plane recording, an aluminum alloy plate or the like is used as a substrate, and a hard Ni-P plated film (film thickness: eg 15
.About.25 .mu.m), the plated film surface is textured, and then a Cr film is formed to an appropriate film thickness (for example, 500 to 3000Å) as a base layer for imparting in-plane anisotropy to the magnetic film. A magnetic film (having a film thickness of, for example, 500 to 2000Å) having the above composition is formed on the surface of the Cr film. Then wear of the magnetic film
As a protective film to prevent damage, a film having lubricity and wear resistance, such as a carbonaceous film (film thickness: for example, 150 to 600
By forming Å), an in-plane recording magnetic disk having a multilayer laminated structure is obtained. The laminated structure is not limited to the above example. For example, by forming a Cr film (film thickness of about 100 to 500Å) on the magnetic film, the weather resistance of the magnetic disk is improved. In addition to forming a carbonaceous film on the surface of the magnetic film, a lubricant (film thickness: 10 to 100Å) is further provided on the surface,
It is also possible to improve the protective lubrication function for the magnetic head. The film formation of each layer can be performed by a sputtering method, an ion plating method, a vacuum vapor deposition method, or the like.

〔Example〕

[I] Manufacture of test magnetic disk Aluminum alloy substrate (outer diameter 130 mm, inner diameter 40 mm, thickness
Ni-P electroless plating film (film thickness 20μ
m) is formed and the surface is polished and textured, and then the underlayer of Cr is formed by magnetron sputtering (however, argon atmosphere pressure: 0.7 × 10 ^-2 torr).
A film, a CoCr-based or CoCrNb-based alloy film as a magnetic film, and a carbonaceous film (film pressure 300 Å) as a lubricating film were laminated in this order to obtain a test magnetic disk. In order to make a proper comparison of the recording / reproducing characteristics (noise characteristics) between the tested magnetic disks, the intrinsic coercive force (Hc), the residual magnetic flux density (Br) and the film thickness (δ The underlayer and the magnetic film were formed so that the product (Br · δ) of () was equal to each other. Its Hc is 1050 Oe, and Br / δ is 450 G / μ.
And

[II] Recording / reproduction characteristic test (noise characteristic test) For each magnetic disk under test, a ferrite head was used to record / reproduce signals at recording linear densities of 20KFCI and 28KFCI, and the reproduction signal output and media noise strength The ratio (S / N, dB) and modulation noise (μVrms) were obtained. The head specifications are: gap width: 18.6μ, gap length: 0.74
μ, inductance: 8μH, flying height: 0.22
μ, loading force: 9.5 gf, and the number of coil turns is 24.

The results of each test magnetic disk test are shown in Table 1 together with the alloy composition of the magnetic film. In the table, No. 11 to 14 are invention examples, N
o.15 is a comparative example, column A shows the case where the recording linear density is 20 KFCI, and column B shows the case where the recording linear density is 28 KFCI.

As is clear from the test results of each of the above examples, CoCrNb
The magnetic disk of the invention example in which the magnetic alloy is a magnetic alloy has improved noise characteristics compared to the conventional product in which a magnetic alloy is a CoCr alloy that does not contain Nb. The higher the value, the more prominent.

[Effects of the Invention] The metal thin film magnetic recording medium for in-plane magnetization recording of the present invention comprises:
Since it has excellent noise characteristics and low recording / reproducing noise, it is possible to achieve high-density recording superior to conventional products, and it is possible to obtain effects such as downsizing of a magnetic recording medium and high quality and high performance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 61-204822 (JP, A) JP-A 63-119017 (JP, A) JP-A 1-213826 (JP, A)

Claims (1)

(57) [Claims] 1. A magnetic recording medium for in-plane magnetization recording, wherein a metallic magnetic film is formed on a non-magnetic substrate via a Cr film, wherein the metallic magnetic film is Co _{1 -XZ} Cr _X Nb _Z [wherein x is 0.07 to 0.15 and z is 0.01 to 0.10.] A metal thin film type magnetic recording medium for in-plane magnetization recording having excellent noise characteristics.