JPH0642281B2 - Perpendicular magnetic recording / reproducing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a perpendicular magnetic recording / reproducing method, and more particularly to a perpendicular magnetic recording / reproducing method capable of increasing a recording / reproducing output.

2. Description of the Related Art Generally, in order to record / reproduce on / from a magnetic recording medium with a magnetic head, the magnetic layer of the magnetic recording medium is magnetized in the longitudinal direction (in-plane direction) of the magnetic recording medium and recorded. The thing to reproduce is general-purpose. However,
It is known that as a result, the demagnetizing field increases as the recording density increases, and the demagnetizing effect adversely affects the high density recording. Therefore, in recent years, as a means for eliminating the above adverse effect, a perpendicular magnetic recording / reproducing system has been proposed in which the magnetic layer of the magnetic recording medium is magnetized in the perpendicular direction. According to this, as the recording density is improved, the demagnetizing field becomes smaller, and theoretically good high density recording in which the residual magnetization does not decrease can be performed.

Conventionally, in this perpendicular magnetic recording / reproducing method, a magnetic head composed of a main magnetic pole and an auxiliary magnetic pole is provided with a perpendicular magnetic recording medium interposed therebetween.
It is configured to generate a strong vertical magnetic field near the tip of the main pole to thereby vertically magnetize the perpendicular magnetic recording medium. Moreover, as a perpendicular magnetic recording medium, Co--
In some cases, a Cr film was formed by sputtering. As is well known, the Co-Cr film has a relatively high saturation magnetization (Ms) and has an easy axis of magnetization perpendicular to the film surface (that is, the coercive force Hc⊥ in the direction perpendicular to the film surface is large. Therefore, it is known that it is an extremely promising material for a perpendicular magnetic recording medium. However, in the Co-Cr film, the easy axis of magnetization of the Co-Cr film has an easy axis of magnetization of the Co-Cr film due to the addition of Cr, and the easy axis of Co (C axis of the close-packed hexagonal crystal) has a nearly vertical orientation. However, it was not sufficiently oriented in the perpendicular direction and a strong perpendicular magnetic anisotropy could not be obtained. Therefore, conventionally, there has been a perpendicular magnetic recording medium having a structure in which the easy axis of Co is strongly oriented in the perpendicular direction by adding a third element such as niobium (Nb) and tantalum (Ta) to Co—Cr. Also Co-C
A high magnetic permeability layer (that is, a layer having a small coercive force Hc, for example, Ni—Fe), which is a so-called backing layer, is separately formed between the r film and the base film to form a two-layer structure and spread in the high magnetic permeability layer. There has been a perpendicular magnetic recording medium having a structure in which the generated magnetic flux is concentrated and sucked toward the magnetic pole of the magnetic head at a predetermined magnetic recording position to achieve a sharp distribution and strong perpendicular magnetization.

Problems to be Solved by the Invention In the above-described conventional perpendicular magnetic recording / reproducing method, in order to strongly orient the easy magnetization axis of Co of the perpendicular magnetic recording medium in the perpendicular direction, Co, Cr, Nb, Ta and the like are added. It was However, although the easy axis of magnetization of Co is strongly oriented in the perpendicular direction by the addition of Cr, Nb, and Ta, it is a ferromagnetic material of Co.
However, the addition of non-magnetic materials such as Cr, Nb, and Ta reduces the saturation magnetization Ms of the perpendicular magnetic recording medium, which makes it impossible to obtain a high reproduction output. Further, when a ring core head is used as the magnetic head, the ring core head contains many in-plane components in the generated magnetic field. Therefore, as described above, the perpendicular magnetic recording medium having only strong anisotropy in the vertical direction is efficient. There is a problem that perpendicular magnetic recording cannot be performed. Further, in the case of a double-layered perpendicular magnetic recording medium formed by using a high-permeability layer as a backing layer in addition to the Co-Cr film, the resistance of the high-permeability layer against the coercive force Hc (700 Oe or more) of the Co-Cr film. Since the magnetic force Hc was extremely small (10 Oe or less), there was a problem that impulsive Barkhausen noise was generated. In addition to this, in order to spin this Barkhausen noise, it is necessary to have a coercive force of at least 10 Oe or more, but there is also a problem that there is no suitable material that satisfies this condition and has a function as a backing layer. there were.

Therefore, in the present invention, attention is paid to the fact that when a magnetic material formed by adding at least one of niobium and tantalum to cobalt and chromium is coated, the magnetic layer is divided into two layers having different coercive forces. It is an object of the present invention to provide a perpendicular magnetic recording / reproducing method which solves the above problems by positively utilizing the lower layer having a lower coercive force in perpendicular magnetic recording and performing perpendicular magnetic recording / reproduction by a ring core head.

Means for Solving the Problems In order to solve the above-mentioned problems, in the present invention, the magnetic force obtained by adding at least one of niobium and tantalum to cobalt and chromium causes resistance magnetic force on the base in the vicinity of the origin. A ring core head is used for a perpendicular magnetic recording medium in which a layer having an in-plane MH hysteresis characteristic represented by a sharply rising curve is formed and a perpendicular magnetization layer is formed on the layer by a magnetic material made of cobalt and chromium. Is used to record / reproduce.

EXAMPLE A perpendicular magnetic recording medium (hereinafter simply referred to as a recording medium) used in a perpendicular magnetic recording / reproducing method according to the present invention is prepared by firstly depositing cobalt (Co), chromium (C) on a base polyimide substrate.
It can be obtained by sputtering a magnetic material obtained by adding at least one of niobium (Nb) and tantalum (Ta) to r) as a target, and then sputtering a magnetic material composed of Co and Cr thereon.

Conventionally, when a metal or the like (eg, Co—Cr alloy) is sputtered on a base, the thin film formed does not form the same crystal structure in the vertical direction on the film surface, but an extremely thin portion near the base. First, a small crystal grain first crystal layer was formed, and then a large crystal grain second crystal layer was formed on top of it, by various experiments (eg, scanning electron microscope photography). (Edward R. Wuori and Professor JHJudy: “INI
TIAL LAYER EFFECT IN CO-C
R FILMS ", IEEE Trans., VOL.MA
G-20, No.5, SEPTEMBER 1984, P774〜
P775 or William G. Haines: “VSMPROFIL
ING OF Co Cr FILMS: A NEW
ANALYTICAL TECHNIQUE "IEEE"
Trans. , VOL, MAG-20, No. 5, SEPT
EMBER 1984, P812-P814).

The present inventor pays attention to the above viewpoint, based on a Co—Cr alloy,
In addition, various metals to which a third element was added were sputtered, and the physical properties of the small-sized crystal layer formed and the large-sized crystal layer formed above were measured. When Nb or Ta is added as the alloy, the coercive force of the small grain size crystal layer is much smaller than that of the large grain size crystal layer, and there is no extreme difference between the coercive force in the vertical direction and in the in-plane direction. I understood. In the present invention, the small grain size crystal layer having the resistance magnetic force is used as an isotropic layer, a Co—Cr film having a large saturation magnetization Ms is formed on the isotropic layer, and this is used as a perpendicular magnetization layer. It is characterized by performing perpendicular magnetic recording and reproduction using a ring core head.

An experiment in which the coercive force of a small grain crystal layer of a magnetic material formed by adding at least one of Co, Cr, Nb and Ta formed by sputtering and a coercive force of a large grain crystal layer were measured by the present inventors The results will be detailed. Co-Cr thin film,
When sputtering the Co-Cr-Nb thin film and the Co-Cr-Ta thin film, the sputtering conditions were set as follows (the sputtering conditions were set equal in each case where Nb or Ta was added).

* Sputtering equipment RF magnetron sputtering equipment * Sputtering method Continuous sputtering. Pre-exhaust pressure was evacuated to 1 × 10 ^-6 Torr and then Ar gas was introduced to 1 × 10 ^-3 Torr * Base polyimide (thickness 20 μm) * Target Co-Cr alloy is used, Nb and Ta are added Was performed by arranging square Nb plates and Ta plates on the required number of Co—Cr alloys.

* The distance between the target and substrate is 110mm. The magnetic characteristics of the thin film are the vibration sample magnetometer (manufactured by Riken Denshi,
The composition of the thin film is an energy dispersive microanalyzer (KEVEX, hereinafter ED).
(Abbreviated as X) and the crystal orientation was measured by an X-ray diffractometer (manufactured by Rigaku Denki).

Addition of Nb as a third element to Co-Cr (2-10 at%
The same phenomenon occurs in the range of addition), and a hysteresis curve in the in-plane direction when a magnetic field of 15 KOe is applied to a recording medium sputtered with a film thickness of 0.2 μm on a polyimide base is shown in FIG. From the figure, it can be seen that the hysteresis curve abruptly and irregularly rises (indicated by the arrow A in the figure) near the zero magnetic field in the in-plane direction, and so-called magnetization jump occurs. Sputtered Co-Cr
Assuming that the -Nb thin film always performs uniform crystal growth during sputtering, the magnetization jump shown in FIG. 1 should not occur, which results in a plurality of Co-Cr-Nb thin films having different magnetic properties. It is assumed that a crystal layer exists.

Then, under the same experimental conditions as shown in FIG.
FIG. 2 shows a hysteresis curve in the in-plane direction when a magnetic field of 15 KOe was applied to a recording medium obtained by sputtering r-Nb on a polyimide base to a film thickness of 0.05 μm. In the figure, it is understood that the magnetization jump of the hysteresis curve as seen in FIG. 1 does not occur and the Co-Cr-Nb thin film with a film thickness of about 0.05 μm is a substantially uniform crystal. . In addition to this, paying attention to the coercive force Hc at a film thickness of about 0.05 μm from the figure, it is understood that the coercive force Hc has a very small value and the magnetic permeability in the in-plane direction is large. From the above results, the coercive force Hc was small in the initial tank that first grew near the base by sputtering, and this initial tank was confirmed by scanning electron microscope photographs (see the above sample). It is considered to be a crystal layer having a diameter. Further, the layer grown above the initial layer has a coercive force Hc larger than the coercive force Hc of the initial layer, and this layer is also a large grain crystal layer confirmed by a scanning electron microscope photograph. Conceivable.

Co-Cr-N in which a small grain size crystal layer and a large grain size crystal layer coexist
The reason why the magnetization jump occurs in the thin film b will be described below with reference to FIGS. 3 to 5. As will be described later, the magnetization jump does not occur in all Co—Cr—Nb thin films with respect to composition ratio and sputtering conditions.
When a Co-Cr-Nb thin film is formed by sputtering under predetermined conditions and a systemistic curve of this thin film is drawn by measurement, a hysteresis curve in which a magnetization jump appears appears as shown in FIG. A hysteresis curve consisting of a very small grain size crystal layer can be obtained by performing sputtering with a small film thickness dimension (about 0.075 μm or less, which will be described later) and measuring it (see FIG. 4). Shown). The large crystal grain layer is considered to have a uniform crystal structure, and the hysteresis curve shown in FIG. 3 is a combination of the hysteresis curve of the small crystal grain layer and the hysteresis curve of the large crystal grain layer. It is considered that the coercive force Hc is larger than that of the small grain size crystal layer, as shown in FIG. 5, and forms a smooth hysteresis curve without magnetization jump. That is, the presence of the magnetization jump shown in FIG. 3 indicates that two layers having different magnetic properties are formed in the same thin film, and thus the Co--Cr shown in FIG. It can be understood that the -Nb thin film also has two layers having different magnetic properties. The coercive force of the large grain crystal layer is determined from the hysteresis curve of the Co—Cr—Nb thin film in which the small grain crystal layer and the large grain crystal layer coexist. It can be obtained from the hysteresis curve obtained by subtracting the curve. According to the above experimental results, when a magnetization jump occurs in the hysteresis curve of the Co-Cr-Nb thin film,
It was proved that two layers having different magnetic properties were formed.

Subsequently, the magnetic properties of each of the two layers formed during the sputtering of the Co-Cr-Nb thin film on the base are determined by Co
It will be described below with reference to FIG. 6 in relation to the thickness dimension of the —Cr—Nb thin film. In FIG. 6, the film thickness dimension of the Co—Cr—Nb thin film is controlled by changing the sputtering time, and the coercive force Hc in the in-plane direction, the coercive force Hc⊥ in the vertical direction, and the magnetization jump amount σj at each film thickness dimension are controlled. They are drawn respectively.

First, paying attention to the coercive force Hc in the in-plane direction,
Extremely small value under 0.08 μm (150 Oe or less)
It is considered that the magnetic permeability in the in-plane direction is high. In addition to this, when comparing the values of the coercive force Hc⊥ in the vertical direction and the coercive force Hc in the in-plane direction, the values are 150 Oe or less for both sides, and the difference is small, and the layer has so-called isotropic properties. . Further, the coercive force Hc does not change greatly even if the film thickness dimension becomes large. Focusing on the magnetization jump amount σj, the magnetization jump amount is 0.075
It sharply rises at μm and draws a smooth downward convex parabola at a film thickness of 0.075 μm or more. Furthermore, focusing on the coercive force Hc⊥ in the vertical direction, the coercive force Hc⊥ is the film thickness dimension.
A sharp rise from 0.05 μm to 0.1 μm shows a high coercive force of 900 Oe or more at a film thickness of 0.1 μm or more. From these results, the boundary between the small grain size crystal layer and the large grain size crystal layer is approximately 0.075 μm.
The small grain size crystal layer having a thickness of 0.075 μm or less is a so-called low coercive force layer having low coercive forces Hc and Hc⊥ in the in-plane direction and the vertical direction. A large grain crystal layer having a thickness of 0.075 μm or more has a low coercive force Hc in the in-plane direction, but has a very high coercive force Hc⊥ in the vertical direction. The layer is suitable for recording.
Further, in the film thickness dimension (0.075 μm or less) where the magnetization jump does not occur, the coercive forces Hc and Hc⊥ in the in-plane direction and the vertical direction are low, and the film thickness dimension larger than this (0.07 μm)
5 μm or more), the coercive force Hc⊥ in the vertical direction
Will increase rapidly. If the magnetization jump also occurs due to this, it is presumed that two layers having different magnetic properties are formed in the Co—Cr—Nb thin film.

Next, Ta is added to Co—Cr as a third element (1 to 10).
The same phenomenon occurs in the addition range of at%), and the result of the same experiment as the above Nb addition is
Shown in the figure. In FIG. 7, the film thickness dimension of the Co-Cr-Nb thin film is controlled by changing the sputtering time, and the coercive force Hc in the in-plane direction, the coercive force Hc⊥ in the vertical direction, and the magnetization jump amount σj at each film thickness dimension. They are drawn respectively. From the figure, when Ta is added to Co-Cr,
A result similar to the case of adding Nb to -Cr is obtained,
The boundary between the small grain crystal layer and the large grain crystal layer is at a film thickness dimension of about 0.075 μm, and the small grain crystal layer having a film thickness dimension of 0.075 μm or less has a coercive force Hc in the in-plane direction and the vertical direction.
, Hc⊥ is low (both Hc and Hc⊥ are 170 Oe or less),
It is a so-called low coercive force layer. In addition to this, the difference between the values of the coercive forces Hc⊥ and Hc in the vertical and in-plane directions is small, and the layer is so-called isotropic. In addition, the film thickness dimension
Coercive force Hc in the in-plane direction for large grain crystal layers of 0.075 μm or more
Although it is low, the coercive force Hc⊥ in the vertical direction is extremely high (750 Oe or more).

It should be noted in the above experiment that the sputtering conditions and the amounts of Nb and Ta added are the above-mentioned values (Nb: 2 to 10).
At%, Ta: 1 to 10 at%), the magnetic jump does not occur, but the magnetic jump does not occur.
Cr-Nb thin film, Co-Cr-Ta thin film and Co-Cr
It means that a small grain size crystal layer and a large grain size crystal layer are also formed in the film (see the above-mentioned reference). An example of the hysteresis curve of the Co-Cr-Nb thin film in which the magnetization jump does not occur is shown in FIG. FIG. 8 (A) is an in-plane direction hysteresis curve including a small grain size crystal layer and a large grain size crystal layer, and FIG. 8 (B) is an in-plane direction hysteresis curve of only the small grain size crystal layer, FIG. 8C is a hysteresis curve in the in-plane direction of only the large grain crystal layer. From each figure, the remanent magnetization Mr _B in the in-plane direction of the small grain crystal layer is the remanent magnetization Mr of the large grain crystal layer.
_Since it is larger than _{C, the} residual magnetization Mr including both crystal layers is Mr.
_A is more disadvantageous than when only the residual magnetization Mr _C of the large grain crystal layer is used, and the anisotropic magnetic field Hk becomes smaller. It is also known that the small grain size crystal layer has poor orientation (large Δθ50),
Also, the coercive force Hc in the in-plane direction is large and is not suitable for perpendicular magnetic recording.

When the Co--Cr--Nb thin film and the Co--Cr--Ta thin film having the small grain size crystal layer and the large grain size crystal layer as described above are considered as the perpendicular magnetic recording medium, the Co--Cr--Nb thin film and the Co--Cr--Nb thin film are used. When it is attempted to perform perpendicular magnetization on a Cr-Ta thin film in the direction perpendicular to the film surface over the entire film thickness, the existence of a small grain size crystal layer is conventionally considered to be an extremely disadvantageous factor for the perpendicular magnetization. (It is a disadvantageous factor in the case where the magnetization jump is generated and the case where the magnetization jump is not generated). That is, the coercive force Hc and Hc⊥ in the in-plane direction and the perpendicular direction are both extremely low (170 Oe or less) in the small grain crystal layer in the case where the magnetization jump occurs, and it is considered that the perpendicular magnetization is hardly generated in this layer. . Further, even in the small grain size crystal layer when the magnetization jump does not occur, the coercive force Hc in the in-plane direction is larger than the coercive force Hc when the magnetization jump occurs, but the coercive force Hc⊥ in the vertical direction is It is considered that there is not enough coercive force to realize perpendicular magnetic recording, and good perpendicular magnetization cannot be achieved. Therefore, even if the magnetization is performed in the direction perpendicular to the film surface, the perpendicular magnetization in the small grain crystal layer is hardly performed, and the perpendicular magnetization efficiency of the entire magnetic film is reduced. This effect is remarkable in a magnetic head such as a ring core head that contains a large amount of in-plane components of magnetic flux.

However, the magnetic characteristics of the small grain size crystal layer in the present invention have a small coercive force Hc in the in-plane direction, a relatively high magnetic permeability and magnetic isotropy.
It has characteristics similar to the backing layer disposed between the Cr film and the base. That is, Co-Cr-Nb thin film and Co-Cr-
In a Ta thin film, it is considered possible to use a small grain size crystal layer having a low coercive force Hc as a so-called backing layer having a high magnetic permeability.

Therefore, the small grain crystal layer formed when a single film of Co—Cr—Nb thin film and Co—Cr—Ta thin film is sputtered functions as a backing layer, and the large grain crystal layer serves as a perpendicular magnetization layer. It is possible to make it function. However, in the single film of Co-Cr-Nb thin film and Co-Cr-Ta thin film, the addition amount of Nb and Ta added to Co-Cr is restricted to a predetermined amount at which a magnetization jump occurs.
Further, by adding Nb and Ta which are non-magnetic materials to Co which is a ferromagnetic material, the saturation magnetization M is higher than that of a Co-Cr film.
Since s decreases, high output perpendicular magnetic recording cannot be performed.

In view of this point, in the present invention, under the condition that the above-mentioned magnetization jump occurs, first, a Co-Cr-Nb thin film or Co is formed on the base.
Form a small grain size crystal layer of -Cr-Ta thin film (approx.
m or less), Co-C having a high saturation magnetization Ms thereon
The r film was sputtered to form a large grain crystal layer that directly contributes to perpendicular magnetic recording. In the Co-Cr film, Cr
Was added at about 5 to 20 at%. In the perpendicular magnetic recording medium having the above-mentioned structure, Co-Cr-Nb is used as the small grain crystal layer.
Various magnetic properties when a thin film is used are compared with a Co-Cr single layer thin film and a Co-Cr-Nb single layer thin film in which a magnetic jump occurs. Fig. 10 shows the relationship between the recording wavelength and the reproduction output of each thin film shown in Fig. 9 when perpendicular magnetic recording / reproduction is performed by a ring core head of Fig. 10), and a Co-Cr-Ta thin film is used as a small grain crystal layer. The various magnetic characteristics when
o-Cr single layer thin film and Co- where magnetization jump occurs
Compared with a single layer thin film of Cr-Ta, the recording wavelength and reproduction output of each thin film shown in FIG. 11 and shown in FIG. 11 when perpendicular magnetic recording and reproduction were performed on this perpendicular magnetic recording medium with a ring core head made of sendust The relationships are shown in FIG. 13, respectively. 9th
FIG. 11 and FIG. 11: Perpendicular magnetic recording in which a Co—Cr large grain crystal layer is formed on a Co—Cr—Nb and Co—Cr—Ta small grain crystal layer formed under the condition that a magnetic jump occurs. The medium (hereinafter, simply referred to as a two-layer medium) is a Co-Cr-Nb thin film single-layer perpendicular magnetic recording medium (hereinafter abbreviated as Nb single-layer medium) in which a magnetization jump occurs and Co-in which a magnetization jump similarly occurs. The saturation magnetization Ms is larger than that of a single-layer perpendicular magnetic recording medium of a Cr-Ta thin film (hereinafter abbreviated as Ta single-layer medium). Also, the coercive force H in the vertical direction
c⊥ has a sufficiently high value and has magnetic properties suitable for perpendicular magnetization. On the other hand, as shown in FIG. 10, the reproduction output and the recording wavelength characteristics are almost the same as those of the Nb single layer medium and the single layer perpendicular magnetic recording medium of Co—Cr thin film (hereinafter abbreviated as Co—Cr single layer medium). Shows a high value in the recording wavelength region of, and a strong reproduction output can be obtained. In particular, in the short wavelength region (the region where the recording wavelength is 1 μm to 0.2 μm), the reproducing output of the Nb single layer medium and the Co—Cr single layer medium is increasing, but the reproducing output of the double layer medium is even higher. Is increasing. Therefore, it can be said that the double-layer medium is particularly suitable for perpendicular magnetic recording / reproduction in the short wavelength region. Similar results were obtained with the Ta dual-layer medium as shown in FIG.

The reason why the above phenomenon occurs will be inferred below with reference to FIG. Co-Cr-Nb and Co-Cr-T satisfying the condition that a magnetic jump occurs on the base 1 such as polyimide.
A magnetic material (hereinafter Co-Cr-Nb and Co-Cr-Ta are collectively referred to as Co-Cr-Nb (Ta)) is about 0.
It is considered that the small grain size crystal layer 2 is formed almost entirely on the Co—Cr—Nb (Ta) thin film coated as described above when sputtered with a film thickness of 1 μm. The small grain size crystal layer 2 has a small coercive force Hc in the in-plane direction and isotropic with little difference from the coercive force Hc⊥ in the vertical direction. Therefore, the small grain crystal layer 2 can be made to have a function substantially similar to that of a so-called backing layer.

On the upper part of the small grain crystal layer 2, a Co—Cr magnetic material of about 0.1 is formed.
Sputtered with a film thickness of μm. When the Co-Cr magnetic material is sputtered on the Co-Cr-Nb (Ta) thin film, the Co-Cr magnetic material and the Co-Cr-Nb are used.
Since the (Ta) thin film has similar properties in crystal structure and composition, Co-Cr is formed at the boundary between both magnetic materials.
The small grain crystal layer of the magnetic material is hardly generated (even if it is generated, it is considered that the thickness does not reach the thickness that affects the perpendicular magnetic recording characteristics), has a high saturation magnetization Ms, and has a strong coercive force in the vertical direction. It is considered that the large grain crystal layer 3 which has the perpendicular magnetization and grows immediately. Therefore, the magnetic flux lines slidably contacting the two-layer medium 4 and emitted from the ring core head 5 pass through the large grain crystal layer 3 to reach the small grain crystal layer 2, and the small grains having the resistance magnetic force and the isotropic property. It is considered that the magnetic flux advances in the in-plane direction in the radial crystal layer 2 and is abruptly absorbed by the magnetic pole portion of the ring core head 5, whereby the large grain crystal layer 3 is perpendicularly magnetized. Therefore, the magnetic loop formed by the magnetic flux has a horseshoe shape as shown by an arrow in FIG. 12, and the magnetic flux concentrates and sharply penetrates the large grain crystal layer 3 having a high saturation magnetization Ms at a predetermined perpendicular magnetic recording position.
Perpendicular magnetization having a large residual magnetization is performed on the large grain crystal layer 3. That is, even in the ring core head 5 that generates a magnetic field containing a large amount of in-plane components, it is possible to perform strong perpendicular magnetic recording with a large residual magnetization, and improve the magnetic recording / reproducing efficiency. The coercive force Hc in the in-plane direction of the small grain size crystal layer 2 is 10 Oe to 50 from FIG. 6 and FIG.
Since it is about Oe and is not a value extremely small with respect to the coercive force Hc⊥ of the large grain crystal layer 3, good perpendicular magnetic recording / reproduction can be performed without generating impact Barkhausen noise.

As described above, according to the perpendicular magnetic recording / reproducing method of the present invention, the magnetic material formed by adding at least one of niobium and tantalum to cobalt and chromium causes the resistance magnetic force to rapidly increase on the base near the origin. A ring core head is mounted on a perpendicular magnetic recording medium in which a layer having an in-plane M-H hysteresis characteristic represented by a curve that rises at the same time is formed and a perpendicular magnetic layer is formed on the layer by a magnetic material made of cobalt and chromium. By adopting a recording / reproducing structure, the perpendicular magnetic recording medium has high coercive force with the lower layer formed on the base which has a small coercive force in the in-plane direction and isotropic and contains at least cobalt and chromium. Since it has a structure in which two layers, that is, an upper layer made of cobalt and chromium having magnetization and a large coercive force in the vertical direction, are formed, The magnetic flux emitted from the pad easily enters the lower layer having a low coercive force and isotropic property and proceeds in the horizontal direction, and then penetrates the upper layer having a high saturation magnetization and a high coercive force to form a ring core head. Since it is abruptly and sharply absorbed by the magnetic pole of, perpendicular magnetic recording / reproduction that can realize high reproduction output can be performed even in a ring core head that generates a strong residual magnetization in the upper layer and generates a magnetic field containing many in-plane components. In addition to this, excellent perpendicular magnetization can be performed especially for a short recording wavelength and a good reproduction output can be obtained, and a magnetization jump occurs in the lower layer, that is, the coercive force in the in-plane direction is small and isotropic. Since it is a layer that has, it surely functions as a so-called backing layer, and its coercive force is not a value that is unnecessarily small compared to the coercive force of the upper layer. Noise has a feature such as can be performed even without good vertical magnetic recording reproducing occur.

[Brief description of drawings]

FIG. 1 is a magnetic film Co-C of one embodiment of a perpendicular magnetic recording medium used in the perpendicular magnetic recording / reproducing method according to the present invention.
FIG. 2 is a diagram showing a hysteresis curve of an r-Nb thin film, FIG. 2 is a diagram showing a hysteresis curve of a small grain crystal layer, and FIGS. 3 to 5 are diagrams for explaining the reason why a magnetization jump occurs.
FIG. 6 is a diagram showing that the Co—Cr—Nb thin film has a two-layer structure and the magnetic characteristics of each layer, and FIG. 7 is a diagram showing Co—Cr.
-A diagram showing that the Ta thin film has a two-layer structure and the magnetic characteristics of each layer. Fig. 8 shows C in which no magnetization jump occurs.
FIG. 9 is a diagram showing an example of a hysteresis curve of an o-Cr-Nb thin film, and FIG. 9 shows various magnetic characteristics when a Co-Cr-Nb thin film is used as a small grain crystal layer of Co-Cr single layer thin film and magnetization jump. The figure shown in comparison with the produced Co-Cr-Nb single layer thin film, FIG. 10 shows the relationship between the recording wavelength and the reproduction output of each thin film shown in FIG. 9, and FIG. 11 shows the small grain size. The figure which showed various magnetic characteristics when using a Co-Cr-Ta thin film as a crystal layer compared with a Co-Cr single-layer thin film and a Co-Cr-Ta single-layer thin film in which a magnetization jump has occurred,
FIG. 12 is a diagram schematically showing a crystal growth state of a perpendicular magnetic recording medium used in the perpendicular magnetic recording / reproducing method according to the present invention and showing a magnetic loop formed by magnetic flux, and FIG. 13 is shown in FIG. It is a figure which shows the recording wavelength of each thin film, and the relationship of reproduction | regeneration output. 1 ... Base, 2 ... Small grain crystal layer, 3 ... Large grain crystal layer, 4 ... Double layer medium, 5 ... Ring core head.

Front Page Continuation (72) Inventor Eiichiro Imaoka 3-12 Moriyamachi, Kanagawa-ku, Yokohama, Kanagawa Japan Victor Company of Japan, Ltd.

Claims (2)

[Claims] 1. An in-plane M-H hysteresis characteristic represented by a curve which has a low coercive force and rapidly rises near the origin on a base by a magnetic material obtained by adding at least one of niobium and tantalum to cobalt and chromium. And a signal is recorded / reproduced by using a ring core head on a perpendicular magnetic recording medium in which a perpendicularly magnetized layer is formed on the layer with a magnetic material made of cobalt and chromium. Perpendicular magnetic recording / reproducing method. 2. The perpendicular magnetic recording / reproducing method according to claim 1, wherein the ring core head is made of Sendust (registered trademark).