JP3039033B2 - Perpendicular magnetic recording / reproducing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perpendicular magnetic recording / reproducing method for a magnetic disk drive, and more particularly to a method for perpendicular recording / reproducing, in which a space between a front end face of a main pole of a head and a perpendicular recording film surface of a medium facing the medium is used. The present invention relates to a perpendicular magnetic recording / reproducing method for reducing and stabilizing reproduction output fluctuations due to fluctuations.

2. Description of the Related Art In a magnetic disk device used as an external storage device of an information processing device, an increase in the amount of information to be recorded is required to increase the recording density and to stabilize the reproduction output to improve the reliability.

[0003]

2. Description of the Related Art As a magnetic disk device for high density recording, a medium capable of recording at a much higher density than a conventionally used horizontal magnetic recording medium, as shown in FIG. A soft magnetic film 13 made of a Ni-Fe alloy and a perpendicular recording film 14 having a perpendicular anisotropy containing Co-Cr as a main component are laminated on a non-magnetic substrate 12 made of a treated aluminum disk. Perpendicular magnetic recording medium 11 having a two-layer film structure and a non-magnetic insulating material on the airflow outflow end face of a ferrite slider partly serving as a magnetic flux return yoke part 22
In the area where 23 is buried, a coil wrapped with an interlayer insulating film
A configuration in combination with a single-pole type magnetic head 21 in which the main magnetic pole 24 and the main magnetic pole 25 are stacked has been studied, and it is well known that it is suitable for high-density recording / reproduction of information.

[0004]

Generally, in high-density recording, the recording medium surface and the recording medium surface are reduced in order to reduce the spacing loss between the pole tip surface of the magnetic head and the recording film surface of the recording medium facing the magnetic head. It is important to narrow the gap between the recording / reproducing magnetic head floating on the medium surface.

In particular, in perpendicular recording / reproducing in a magnetic disk device capable of high-density recording as described above, the leading end face of the main pole of the single-pole type magnetic head 21 and the perpendicular magnetic recording medium for recording density characteristics, reproduction output, etc. The effect of the spacing between the surface 11 and the perpendicular recording film 14 is extremely large, and there is a problem how to eliminate the effect of the minute fluctuation of the spacing.

The present invention has been made in view of the above-mentioned conventional problems, and has been made in view of the above-described conventional problems. It is an object of the present invention to provide a novel perpendicular magnetic recording / reproducing method for stabilizing the reproduction output by reducing the fluctuation of the reproduction output.

[0007]

In order to achieve the above object, the present invention provides a two-layer film structure in which a perpendicular recording film having a perpendicular anisotropy containing Co-Cr as a main component is laminated on a soft magnetic film. A method for recording / reproducing information by floating a single-pole type magnetic head having a main pole and a magnetic flux return portion on a surface of a perpendicular magnetic recording medium, comprising the steps of: The distance from the surface of the perpendicular recording film of the medium is s, the thickness of the perpendicular recording film is t, the saturation magnetic flux density of the perpendicular recording film is 4πMs, and the coercive force perpendicular to the film surface of the perpendicular recording film is Hc. Then, it is configured to satisfy the relational expression of (4πMs / Hc) −1 <t / s.

[0008]

According to the present invention, a so-called head-medium system combining the perpendicular magnetic recording medium having the two-layer film structure and a single-pole type magnetic head is regarded as one magnetic circuit as shown in FIG.
By calculating the permeance coefficient Pr of the system, the recording operation point of the perpendicular recording film of the perpendicular magnetic recording medium can be estimated.

The permeance coefficient Pr is such that the thickness of the tip of the main pole 25 of the single pole type magnetic head 21 is Tm, the width of the tip of the main pole 25 is Tw, the thickness of the perpendicular recording film 14 of the perpendicular magnetic recording medium 11 is T, the spacing between the tip of the main pole of the single-pole type magnetic head 21 and the surface of the perpendicular recording film 14 of the perpendicular magnetic recording medium 11 having the two-layer film structure, and the spacing s, the main pole 25, and the magnetic flux. Assuming that the magnetic resistance of the entire magnetic circuit system (excluding the perpendicular recording film) such as the return yoke portion 22 and the soft magnetic film 13 is Rtotal, it can be obtained by the following relational expression.

Pr = t / (Tm.Tw.Rtotal) Rtotal is mainly the value of the single pole type magnetic head 21 when the magnetic permeability μ of the magnetic body on the side of the single pole type magnetic head 21 is sufficiently large. because it is occupied by the magnetic resistance between the main magnetic pole 25 and the perpendicular recording film 14, the magnetic permeability of air at a spacing When mu _0, can be approximated as follows.

[0011] _{Rtotal ≒ 1 / μ 0 · Tm} · Tw / s permeance coefficient Pr From this equation can be represented approximately by the following equation. Pr ≒ t / s Next, the operating point during recording on the BH loop of the perpendicular magnetic recording medium 11 having the above relationship will be described with reference to FIG.

FIG. 2 shows Co-Cr in the perpendicular magnetic recording medium 11.
BH loop of the perpendicular recording film 14 composed of
Is given by the following equation, where M is the magnetization of the perpendicular recording film 14 made of Co—Cr, and H is the applied magnetic field.

B = 4πM + μ ₀ H Thus, the permeance Prc passing through the shoulder point (C) of the BH loop is such that the saturation magnetic flux density of the perpendicular recording film 14 made of Co-Cr is 4πMs, Assuming that the coercive force is Hc, it is expressed by Prc = (4πMs / Hc) −1.

Here, when Prc> Pr, the point (A) of the BH loop in FIG. 2 is a magnetization to be recorded by the following relational expression. In the case of perpendicular magnetization reversal recording, the medium demagnetizing field after recording is Since the magnetic flux becomes smaller and the magnetic flux from the single-pole type magnetic head 21 passes through the perpendicular recording film 14, this magnetization is stored as it is in the perpendicular recording film 14, so that a reproduction output corresponding to the magnetization can be expected.

(4πMs / Hc) -1> Pr ≒ t / s In this case, the permeance coefficient Pr fluctuates in accordance with the fluctuation of the spacing s, so that the point (A) moves. Therefore, the fluctuation of the reproduction output due to the fluctuation of the spacing increases.

However, when Prc <Pr, the operating point of the BH loop in FIG. 2 moves to the point (B) by the following relational expression.
The fluctuation of the magnetization due to the fluctuation of the permeance coefficient Pr is reduced. (4πMs / Hc) -1 <Pr ≒ t / s Therefore, the fluctuation of the reproduction output due to the fluctuation of the spacing becomes small. Therefore, the present invention relates to the single-pole type magnetic head 21 based on the above principle and the perpendicularity of the two-layer film structure. By recording and reproducing information in combination with the magnetic recording medium 11,
Reducing the fluctuation of the reproduction output with respect to the minute fluctuation of the spacing s between the tip of the main pole of the single-pole type magnetic head 21 and the perpendicular recording film surface of the perpendicular magnetic recording medium 11 having the double-layered film structure, thereby stabilizing the reproduction output. be able to.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. In this embodiment, for example, the coercive force Hc in the direction perpendicular to the film surface is 1500 Oe, and the saturation magnetic flux density 4πMs is 4500 Gau.
A perpendicular magnetic recording medium having a two-layer film structure having a perpendicular recording film mainly composed of Co-Cr having a thickness of 0.10 μm and a 0.15 μm film having the same coercive force Hc and saturation magnetic flux density. The two configurations in which a perpendicular magnetic recording medium having a two-layer film structure provided with a perpendicular recording film containing Co-Cr as a main component and a single-pole type magnetic head are each described based on the principle described above (4π
Ms / Hc) -1 <Pr ≒ t / s When the reproduction output fluctuation with respect to the spacing fluctuation is calculated based on the relational expression, (4πMs / Hc) -1 = (4500/1500) -1 = 2 0.15 μm In a perpendicular magnetic recording medium having a perpendicular recording film having a film thickness, since 2 <Pr ≒ t / s = 0.15 / s, s <0.075, that is, when the spacing s is 0.075 μm or less, the reproduction for the spacing is performed. Output fluctuation is reduced.

In a perpendicular magnetic recording medium having a perpendicular recording film having a thickness of 0.10 μm, since 2 <Pr ≒ t / s = 0.10 / s, s <0.05, that is, the spacing s is 0.05 μm or less. In this case, the fluctuation of the reproduction output with respect to the spacing becomes small.

With respect to such a result, the above-mentioned film thickness is
Combine a perpendicular magnetic recording medium with a perpendicular recording film whose main component is Co-Cr different from 0.10 μm and 0.15 μm, and a single pole type magnetic head, and measure the reproduction output of each by actually changing the spacing s In FIG. 3 showing the dependency of the thickness t of the perpendicular recording film and the spacing of the reproduction output on the perpendicular recording film, a perpendicular magnetic recording medium having a perpendicular recording film Then, when the spacing s is 0.05 μm or more, there is no phenomenon that the fluctuation of the reproduction output with respect to the fluctuation of the spacing becomes small, and this is consistent with the analysis result based on the above-described principle.

On the other hand, as shown by the solid line curve in the figure, in the perpendicular magnetic recording medium provided with the perpendicular recording film having a thickness of 0.15 μm, the slope of the curve at the spacing of 0.075 μm or less is extremely small, and the reproduction is not performed. It was confirmed that the fluctuation of the output became small and coincided with the analysis result based on the principle described above.

The saturation magnetic flux density 4πMs is 4500 Gauss.
A perpendicular recording film having a coercive force Hc of 700 Oe in the direction perpendicular to the film surface and a main component of Co-Cr having a thickness of 0.2 μm and a saturation magnetic flux density of 4πMs of 4500 Gauss, Combination of a single-pole type magnetic head and two perpendicular magnetic recording media of two-layer film structure, each having a Co-Cr-based perpendicular recording film with a coercive force Hc of 1500 Oe and a thickness of 0.2 μm. The configuration was explained based on the above principle (4πMs / Hc)
Calculating the variation of the reproduction output with respect to the variation of the spacing based on the relational expression of -1 <Pr ／ t / s, the perpendicular magnetic recording medium provided with the perpendicular recording film having the coercive force Hc of 700 Oe is (4πMs / Hc). -1 = (4500/700) -1 = 5.43 Since the thickness of the perpendicular recording film is 0.2 μm, s <0.037 from 5.43 <Pr ≒ t / s = 0.2 / s.

That is, when the spacing s is 0.037 μm or less, it is expected that the fluctuation of the reproduction output will be small.
On the other hand, in a perpendicular magnetic recording medium provided with a perpendicular recording film having a coercive force Hc of 1500 Oe, (4πMs / Hc) −1 = (4500/1500) −1 = 2 because the thickness of the perpendicular recording film is 0.2 μm. S <0.10 from 2 <Pr ≒ t / s = 0.2 / s.

That is, when the spacing s is 0.10 μm or less, the fluctuation of the reproduction output with respect to the spacing s is small. In response to this result, the coercive force Hc was 700
Oe and 1500 Oe were combined with a perpendicular magnetic recording medium with a perpendicular recording film whose main component was Co-Cr different from a single pole type magnetic head, and the reproduction output was measured while actually changing the spacing s. However, the coercive force of the perpendicular recording film
In FIG. 4 showing the dependency of Hc and the reproduction output on the spacing, the coercive force of 700 Oe is shown as the curve indicated by the broken line in the figure.
In a perpendicular magnetic recording medium provided with a perpendicular recording film having Hc,
When the spacing s is 0.05 μm or more, there is no phenomenon that the fluctuation of the reproduction output with respect to the fluctuation of the spacing becomes small.
This is consistent with the analysis result based on the above principle.

On the other hand, as shown by a solid line curve in the figure, in a perpendicular magnetic recording medium having a perpendicular recording film having a coercive force Hc of 1500 Oe, the slope of the curve at a spacing of 0.10 μm or less becomes extremely small. In addition, it was confirmed that the fluctuation of the reproduction output became small and coincided with the analysis result based on the above principle.

[0025]

As is apparent from the above description, according to the perpendicular magnetic recording / reproducing method of the present invention, the soft magnetic film
When the flying distance of a single-pole type magnetic head with respect to the surface of a perpendicular magnetic recording medium having a two-layer structure in which perpendicular recording films having perpendicular anisotropy containing Co-Cr as a main component are laminated is reduced slightly, The distance between the tip of the main pole of the type magnetic head and the surface of the perpendicular recording film of the perpendicular magnetic recording medium is s, the thickness of the perpendicular recording film is t, the saturation magnetic flux density is 4πMs, and the surface of the perpendicular recording film is When the coercive force in the vertical direction is Hc, (4πMs / Hc)
By satisfying the relational expression of -1 <t / s, reproduction with respect to minute fluctuations in spacing between the leading end surface of the main pole of the single-pole type magnetic head and the perpendicular recording film surface of the perpendicular magnetic recording medium is performed. Output fluctuations can be reduced,
It can be stabilized.

Therefore, excellent effects such as improvement in reliability in high-density recording can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining the principle of a perpendicular magnetic recording / reproducing method according to the present invention by regarding a head / medium system as a magnetic circuit.

FIG. 2 is a diagram for explaining a recording operation point on a BH loop of a perpendicular recording film made of Co—Cr of a perpendicular magnetic recording medium.

FIG. 3 is a diagram showing the spacing t of the thickness t of the perpendicular recording film made of Co-Cr and the reproduction output according to the present invention.

FIG. 4 is a diagram showing the spacing dependency of the coercive force Hc and the reproduction output of the perpendicular recording film made of Co—Cr according to the present invention.

FIG. 5 is a schematic configuration diagram for explaining a conventional perpendicular magnetic recording / reproducing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Perpendicular magnetic recording medium 12 Non-magnetic substrate 13 Soft magnetic film 14 Perpendicular recording film 21 Single pole type magnetic head 22 Magnetic flux return yoke part 25 Main pole

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-99905 (JP, A) JP-A-59-14101 (JP, A) JP-A-59-168902 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G11B 5/02 G11B 5/127

Claims (1)

(57) [Claims] A perpendicular magnetic recording medium (11) having a two-layer structure in which a perpendicular recording film (14) having Co-Cr as a main component and having perpendicular anisotropy is laminated on a soft magnetic film (13). A single pole type magnetic head (21) having a main pole (25) and a magnetic flux return yoke (22)
In the method of recording and reproducing information by floating, the distance between the front surface of the main pole of the single-pole type magnetic head (21) and the surface of the perpendicular recording film (14) of the perpendicular magnetic recording medium (11) is s, Assuming that the thickness of the perpendicular recording film (14) is t, the saturation magnetic flux density of the perpendicular recording film (14) is 4πMs, and the coercive force perpendicular to the film surface of the perpendicular recording film (14) is Hc, A perpendicular magnetic recording / reproducing method characterized by satisfying the relationship of the formulas. (4πMs / Hc) -1 <t / s