JP2001060311A - Disk media - Google Patents

Abstract

(57) [Problem] To provide a disk medium whose magnetic recording layer is made of an alloy of a rare earth metal and a transition metal can be applied to a magnetic disk device. SOLUTION: The magnetic recording layer 3 of the disk medium is made of an alloy of a rare earth metal and a transition metal, and the compensation temperature is 80 ° C. or higher and Curie temperature or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a disk medium in which an alloy of a rare earth metal and a transition metal is used as a magnetic recording layer,
And a disk device having the disk medium.

[0002]

2. Description of the Related Art As a material of a magnetic recording layer of a magnetic disk applied to a magnetic disk device, a CoCr alloy such as CoCrPtTa having in-plane magnetization properties is widely used. However, in in-plane recording on a CoCr-based material, when the recording density is increased, the S / N of the reproduced signal decreases, and an error occurs in reading recorded data. In order to prevent a reduction in S / N due to high-density recording, a method of reducing the demagnetizing field from the bit boundary by making the magnetic recording layer thinner and a method of reducing noise by reducing the crystal grain size have been adopted. Have been.

[0003] Although the S / N ratio can be improved by the above-described method, there arises a problem that storage reliability of recorded data is reduced. That is, a problem of thermal fluctuation occurs. The effect of thermal fluctuation is indicated by Ku · V / kT. Where K
u is the magnetic anisotropy constant of the magnetic recording layer, V is the volume of magnetic particles in the recording layer, and k is the Boltzmann constant. From this equation, S
When the crystal grains are made small for improving the / N ratio, the crystal grains are easily affected by thermal fluctuation. Also, making the magnetic recording layer thinner involves a reduction in the volume of the magnetic grains, so that the magnetic recording layer is also more susceptible to thermal fluctuations. If it becomes susceptible to thermal fluctuations, the direction of recording magnetization becomes unstable, and data cannot be read. In particular, since the temperature inside the disk drive during operation is as high as 60 ° C. or more, the influence of the thermal fluctuation is further increased, and the reliability of data retention is rapidly lowered.

As a method of solving the problems of noise generation due to crystal grains and reduction in data retention reliability due to thermal fluctuation, adoption of an alloy of a rare earth metal and a transition metal as a material for a magnetic recording layer has been considered. Since an alloy of a rare earth metal and a transition metal is amorphous, noise due to crystal grains does not originally occur. For example, Japanese Patent Application Laid-Open No. 58-1653
No. 06 discloses that 10 to 40 at% of Gd, Tb, Dy
And 60 to 90 at% of Fe, Co, N
It is disclosed that the magnetic recording layer is composed of an alloy of a transition metal such as i.

[0005]

Incidentally, the recording density of magnetic disk media in recent years has been greatly improved.
The recording bit diameter has also been reduced to about 0.1 to 1.0 μm.

However, Japanese Patent Application Laid-Open No. 58-165306 discloses the above.
Or Ty or Dy in the composition range disclosed in
Is 30 at% or more, the coercive force at room temperature (25 ° C.) is 1 kOe or less, and it is difficult to stably provide small recording bits. Further, when the composition of Tb is 20
At ２５25 at%, the coercive force at room temperature is 10 kOe or more. In a method of recording data by lowering the coercive force by heating the medium, such as a magneto-optical disk device, recording is possible even if the coercive force is large, but in a magnetic disk device without heat assist, If the coercive force is too large, it is difficult to record with a magnetic head.

Further, GdFe or GdFeCo has extremely small perpendicular magnetic anisotropy and a coercive force of 1 kOe or less in most of the above composition ranges, so that high-density recording is difficult.

In order to increase the recording density in recording on a magnetic disk, it is generally necessary to move the recording / reproducing head closer to the magnetic recording layer. for that purpose,
The thickness of the protective layer formed on the magnetic recording layer needs to be small. However, the above-mentioned Tb has the property of being the most active in oxygen among the rare earth metals, so it is necessary to ensure a sufficient thickness of the protective layer. As a result, the head cannot be brought close to the protective layer, making high-density recording difficult.

Accordingly, a first object of the present invention is to provide a disk medium having a high recording density.

A second object of the present invention is to provide a disk medium having a high S / N.

A third object of the present invention is to provide a disk medium having high data retention reliability.

A fourth object of the present invention is to provide a disk medium in which data can be easily recorded by a magnetic head.

[0015] A fifth object of the present invention is to provide a disk medium capable of reducing the flying height of a head.

[0014]

In an alloy of a rare earth metal and a transition metal, the magnetization of the rare earth metal and the magnetization of the transition metal are in opposite directions, and the magnetization of the medium as a whole is the magnetization of the rare earth metal and the magnetization of the transition metal. Is equivalent to the difference Also, in general,
Although the magnetization of a magnetic material decreases with an increase in temperature, an alloy of a rare earth metal and a transition metal has the same magnitude of magnetization at a specific temperature. The temperature is called a compensation temperature. At the compensation temperature, the magnetization becomes zero and the coercive force shows a very large value. The present invention aims to improve the performance of a disk medium having an alloy of a rare earth metal and a transition metal as a recording magnetic layer by setting the compensation temperature to an optimum value.

In the disk medium of the present invention, an alloy of a rare earth metal and a transition metal is used as the magnetic recording layer.
It satisfies the relationship of ° C ≦ compensation temperature ≦ Curie temperature.

In the above disk medium, since the magnetic recording layer is amorphous, no noise is caused by crystal grains. In addition, the coercive force is 1 kOe to 10 kOe in the range of room temperature (25 ° C.) to 80 ° C. when the compensation temperature is outside the normal temperature range where the magnetic disk device is placed, and the extremely large coercive force is reduced. Not even. Therefore, the magnetic head can record data on the disk medium without thermal assist, and secures a coercive force enough for the magnetic bits to be thermally stable. Further, the fluctuation width of the coercive force with respect to the temperature change is small, and the control of the magnetic field of the magnetic head required for recording becomes easy.

With the above-described features, high-density recording can be performed, and good recording and reproduction can be performed in combination with a magnetic disk drive.

The magnetic recording layer is made of, for example, Dy _x
(Fe _1-y Co _y ) _1-x and the composition is 0.26 ≦
It can be realized by satisfying x ≦ 0.30 and 0.25 ≦ y <1.0. Further, since Dy is a material that is hardly oxidized, the thickness of the protective layer formed on the magnetic recording layer may be reduced. As a result, the distance between the magnetic head and the magnetic recording layer can be reduced, and high-density recording can be performed.

In particular, Dy is resistant to oxidation, and it is sufficient that the protective film formed on the magnetic recording film has a thickness of 10 nm. Since the protective layer is thin, the distance between the magnetic head and the magnetic recording layer becomes short. Therefore, the use of Dy as a rare earth metal is effective for high density recording.

[0020]

FIG. 1 shows a cross section of a disk medium according to the present invention. That is, the magnetic recording layer 3 and the protective layer 4
Are sequentially stacked. Hereinafter, each layer of the disk medium will be described.

The substrate 1 is made of a non-magnetic material and has a disk shape. Examples of the material forming the substrate 2 include an aluminum (including aluminum alloy) substrate, a glass (including tempered glass) substrate, a silicon substrate having a surface oxide film,
It includes an iC substrate, a carbon substrate, a plastic substrate, a ceramic substrate, and the like.

In general, the substrate 1 is covered with Si
An N layer or a NiP layer 2 is formed. Here, if the substrate 1 is made of glass, the SiN layer is formed by reactive DC magnetron sputtering using a single crystal of Si as a target and introducing a mixed gas of Ar and N ₂ . The NiP layer is made of Ni
The film is formed by DC magnetron sputtering using P as a target and introducing Ar gas. If the substrate is made of aluminum or plastic, the NiP layer is preferably formed by plating.

Here, the plastic substrate has the advantage that it is less expensive than the aluminum substrate or the glass substrate, but has low heat resistance, and the magnetic recording layer disposed thereon has a room temperature (2 ° C.).
5 ° C.). However, in a disk medium using a CoCr alloy as a magnetic recording layer,
If the magnetic recording layer is formed at room temperature, sufficient magnetic properties cannot be obtained. On the other hand, the magnetic recording layer of the present invention comprising an alloy of a rare earth metal and a transition metal can obtain sufficient magnetic properties even when formed at room temperature, and can reduce the cost by using an inexpensive plastic substrate.

The size of the substrate 1 is determined according to the type of a desired medium and the disk device to which the substrate 1 is applied. Generally, the diameter is 1 inch to 3.5 inches, and the thickness is 0.5 mm.
１．０1.0 mm.

In the case of a disk medium using a CoCr-based alloy as the magnetic recording layer, it was useful to subject the substrate surface to texture processing along the circumferential direction.
By the texture processing, the direction of easy magnetization of the magnetic recording layer is further oriented in the circumferential direction, and a high S / N ratio can be obtained. But,
As in the present invention, since the magnetic recording layer made of an alloy of a rare earth metal and a transition metal is a perpendicular magnetization film, texture processing for giving anisotropy in the in-plane circumferential direction is not required, but rather causes noise.

The magnetic recording layer 3 is made of an alloy of a rare earth metal and a transition metal. At room temperature (25 ° C.), the magnetic characteristics are such that the sub-lattice magnetization of the rare earth metal is dominant (the magnetization of the rare earth metal is larger than the magnetization of the transition metal). Thus, the coercive force of the entire medium increases as the temperature increases. Further, between the Curie temperature _Tc and the guaranteed temperature _Tcomp , 80 ° C
The relationship of ≦ T _comp ≦ T _c holds. Specific materials include Dy _x (Fe _1-y Co _y ) _1-x , and the composition may satisfy 0.26 ≦ x ≦ 0.30 and 0.25 ≦ y <1.0. desirable.

The magnetic recording layer 3 is generally formed by a sputtering method such as a magnetron sputtering method. As a film forming condition, it is preferable to form a film at room temperature under an Ar gas pressure of 10 mTorr. In forming a film of DyFeCo, sufficient magnetic properties can be obtained even at room temperature, unlike the film formation of a CoCr-based alloy. Also, no bias is required. As other film forming methods instead of the sputtering method, for example, a vapor deposition method, an ion beam sputtering method and the like can be mentioned.
The thickness of the magnetic recording layer 3 is preferably 30 nm to 150 nm. When the thickness of the magnetic recording layer 3 is 30 nm or less, the magnetic flux leaking from the disk medium becomes small, and the intensity of the reproduced signal decreases. On the other hand, when the thickness of the magnetic recording layer 3 is 1
If it is 50 nm or more, the recording medium becomes susceptible to a demagnetizing field, and the recording becomes unstable. In order to improve the corrosion resistance of DyFeCo, Cr or the like may be added as needed. Gd or Tb is used to adjust the coercive force.
Can be added to Dy. Here, the coercive force decreases by adding Gd, and increases by adding Tb.

The protective layer 4 is made of carbon alone or a compound containing carbon, for example, WC, SiC, B ₄
C, hydrogen-containing carbon, and diamond-like carbon (DLC), which has attracted attention because of its high hardness. The protective layer 4 is preferably formed by a sputtering method such as a magnetron sputtering method. Suitable film forming conditions include, for example, a film forming temperature of room temperature to 100 ° C.
Ar gas pressure of 10 to 10 mTorr. Also,
Instead of the sputtering method, another film forming method, for example, an evaporation method, an ion beam sputtering method, or the like may be used. If the thickness of the protective layer 6 is too small, the magnetic recording layer 3 is easily oxidized. For example, when Tb is used as the rare earth metal of the magnetic recording layer 3, the protective layer 4 has a thickness of 15 nm to prevent oxidation.
Although it is necessary as described above, when Dy is used, 10 nm is sufficient. If the protective layer 4 is too thick, the distance between the head and the magnetic recording layer 3 increases, making high-density recording difficult. Therefore, it is ideal from the viewpoint of high-density recording to use Dy, which requires a relatively thin protective layer 4 as the rare earth metal of the magnetic recording layer 3.

Incidentally, a lubricating film may be formed on the protective layer 4 in order to smooth the surface of the disk medium. The lubricating film is made of a fluorocarbon resin-based material and has a film thickness of 0.
5 nm to 2 nm. The lubricating film forms a lubricant film on the recording medium by immersing the disk medium in a solution containing the above materials. The film thickness depends on the concentration of the material in the solution and the speed at which the medium is pulled out of the solution.

Further, the present invention resides in a disk device on which the above-mentioned disk medium is mounted. In the disk device of the present invention, the structure is not particularly limited, but basically, a magnetic head including a recording head unit for recording information on a disk medium and a reproducing head unit for reproducing information. Is included. In particular, it is preferable that the reproducing head includes a magnetoresistive head using a magnetoresistive element whose electric resistance changes according to the strength of a magnetic field, that is, an MR head.

In the magnetic head in the disk drive of the present invention, the recording head and the reproducing head are shown in FIGS.
A laminated structure as shown in FIG. FIG. 2 is a side sectional view of the magnetic head, and FIG. 3 is a line segment BB of FIG.
FIG. The magnetic head shown in FIGS. 2 and 3 is mainly used for in-plane recording, but also generates a magnetic field in the vertical direction, so that it can also be recorded on a perpendicular magnetic recording medium.

As shown in FIGS. 2 and 3, the magnetic head comprises an inductive recording head section 11 for recording information,
Magnetoresistive read head 1 for reading information
Have one. The recording head unit 11 includes a lower magnetic pole (upper shield layer) 13 made of NiFe or the like, and an upper magnetic pole 14 made of NiFe or the like opposed to the lower magnetic pole 13 at a fixed interval.
And a coil 15 that excites the magnetic poles 13 and 14 and causes the magnetic recording medium to record information at the recording gap.

The reproducing head section 12 is preferably constituted by an AMR head, a GMR head or the like.
On the magnetoresistive element section 12A of the reproducing head section 12,
A pair of conductor layers 16 for supplying a sense current to the magnetoresistive element section 12A are provided at intervals corresponding to the recording track width. Here, the thickness of the conductor layer 16 is
The portion 16A near the magnetoresistive element portion 12A is formed thin, and the other portion 16B is formed thick.

In the structure shown in FIGS. 3 and 3, since the thickness of the conductor layer 16 is small in the portion 16A near the magnetoresistive element portion 12A, the curvature of the lower magnetic pole (upper shield layer) 13 and the like is small. Has become. Therefore, the shape of the recording gap facing the magnetic recording medium is not so curved, and even if the position on the track of the magnetic head during recording of information and the position on the track of the magnetic head during reading are slightly shifted, The magnetic disk device can read information accurately. Therefore, it is possible to avoid a situation in which a read error occurs even though the allowable off-track amount is small.

On the other hand, since the thickness of the conductor layer 16 is formed thicker in the portion 16B other than the vicinity of the magnetoresistive element portion 12A, the resistance of the conductor layer 16 can be reduced as a whole. A change in resistance of the magnetoresistive element portion 12A can be detected with high sensitivity, the S / N ratio is improved, and heat generation in the conductor layer 16 can be avoided.
The generation of noise due to heat generation can also be prevented.

In the above-described magnetoresistive effect type magnetic head, after forming a large number of them on a ceramic head substrate by using a thin film technique, the head substrate is cut out for each head and processed into a predetermined shape. Can be manufactured by

Further, the disk device of the present invention is as shown in FIGS. 4 is a plan view of the disk device (with the cover removed), and FIG. 5 is a cross-sectional view taken along line AA of FIG.

The magnetic disk 50 includes a base plate 51
It is driven by a spindle motor 52 provided above. In the present embodiment, three disk media are provided.

The driving actuator 53 for supporting the head slider is rotatably supported on the base plate 51. At one end of the actuator 53, a plurality of head arms 54 extending in a direction parallel to the recording surface of the disk 50 are formed. At one end of the head arm 54,
The suspension 55 is attached. The head slider 1 is attached to a flexure portion of the suspension 55 via an insulating film (not shown). A coil 57 is attached to the other end of the actuator 53.

A magnetic circuit 58 comprising a magnet and a yoke is provided on the base plate 51, and the coil 57 is disposed in a magnetic gap of the magnetic circuit 58. The magnetic circuit 58 and the coil 57 constitute a moving coil type linear motor (VCM: voice coil motor). The upper portions of the base plates 51 are covered with a cover 59.

Next, the operation of the disk device having the above configuration will be described. When the disk 50 is stopped, the slider 40 contacts the retraction zone of the disk 50 and stops.

Next, when the magnetic disk 50 is driven to rotate at a high speed by the spindle motor 52, the slider 40 flies from the disk surface at a minute interval due to the air flow generated by the rotation of the magnetic disk 50.
When a current is applied to the coil 57 in this state, a thrust is generated in the coil 57, and the actuator 53 rotates. As a result, the head (slider 40) can be moved to a desired track on the magnetic disk 50 to read / write data.

In this magnetic disk drive, since the conductor layer of the magnetic head is formed thinner in the vicinity of the magnetoresistive element and thicker in the other part, the curvature of the magnetic pole of the recording head is reduced. As the resistance is reduced, the resistance of the conductor layer is reduced, and information can be read accurately and with high sensitivity if the off-track is in a small range.

[0044]

EXAMPLE In this example, a disk medium having a cross section shown in FIG. 1 was manufactured under the following conditions. In this embodiment, a DC magnetron sputtering apparatus 10 as shown in FIG. 6 was used for forming the NiP layer 2, the magnetic recording layer 3, and the protective layer 4. The sputtering device 20
As shown, a gas supply port 21 for introducing a gas into the sputtering chamber, an exhaust port 22, a susceptor 23 for supporting a substrate,
A target 24 and a magnet 25 are provided. 1. Preparation of Disk Medium On a disk-shaped glass substrate 1 having a chemically strengthened and well-cleaned surface, the NiP layer, D
y _x (Fe ₆₅ Co ₃₅ ) _1-x and a protective layer were sequentially formed.

First, the substrate 1 is placed in a NiP chamber, and a DC using a preset NiP target is set.
The NiP layer 2 was formed by magnetron sputtering.
Before forming the NiP layer 2, the inside of the chamber was 5.0 × 10
^The gas was evacuated to ^-7 Torr or less, and then kept at 5.0 × 10 ^-3 Torr by introducing Ar gas. In this state, a 90 nm-thick NiP layer 2 was formed on the substrate 1. The thickness of the NiP layer 2 is controlled by adjusting the power supplied to the NiP target.

The glass substrate 1 on which the NiP layer 2 is formed,
Dy _x (Fe _1-y Co _y ) transferred to a DyFeCo deposition chamber and having various combinations of x and y
_The magnetic recording layer 3 was formed by DC magnetron sputtering using a _1-x target. Before the formation of the magnetic recording layer 3, the inside of the chamber is evacuated to 5.0 × 10 ⁻⁷ Torr or less, and then 5.0 × 10 ⁻⁷ by introducing Ar gas.
^-3 Torr. In this state, a magnetic recording layer 3 having a thickness of 30 nm was formed on the NiP layer 2. The thickness of the magnetic recording layer 3 is controlled by adjusting the power supplied to the Dy _x (Fe _1-y Co _y ) _1-x target.

Glass substrate 1 on which magnetic recording layer 3 is formed
Is transferred to a carbon film forming chamber, and the protective layer 4 is formed by DC magnetron sputtering using a carbon target.
Was formed. Before forming the protective layer 4, the inside of the chamber is evacuated to 5.0 × 10 ⁻⁷ Torr or less.
By introducing a mixed gas of Ar, H ₂ and N ₂ , 5.0
× 10 ⁻³ Torr. The mixing ratio of Ar, H ₂ and N ₂ is 80: 17: 3. In this state, a DLC layer 4 (protective layer) having a thickness of 10 nm was formed on the magnetic recording layer 3. The thickness of the protective layer 4 is controlled by adjusting the power supplied to the carbon target.

Through the steps described above, a disk having a cross section shown in FIG. 1 was produced. 2. Evaluation of Disk FIG. 7 is a graph showing the temperature dependence of the coercive force (Hc) in Dy ₂₇ (Fe ₆₅ Co ₃₅ ) ₇₃ .

As shown in FIG. 7, at room temperature, Hc is about 3 kOe. In the range up to 80 ° C., Hc gradually increases with the rise of temperature.
In the range of １００100 ° C., the temperature rises sharply as the temperature rises. The maximum point of Hc, 100 to 120 ° C., is the compensation temperature T _comp . Under the compensation temperature, the coercive force becomes too large and cannot be measured by a general magnetic property measuring device. Therefore, the characteristic line is interrupted in the section of the compensation temperature. The same applies to FIGS. 8 and 11 described later. In a range _{equal to} or higher than T _comp , Hc decreases as the temperature rises, reaches a Curie temperature (Tc) at about 220 ° C., and the magnetism disappears.

The temperature inside the disk drive is 6
It rises to about 0 ° C. Since a disk medium using a CoCr-based alloy as the magnetic recording layer has a property that Hc decreases as the temperature increases, there is a problem that the recording bit becomes thermally unstable due to an increase in the temperature in the disk drive. On the other hand, as shown in FIG.
_{In a} disk medium using a magnetic recording layer made of ₂₇ (Fe ₆₅ Co ₃₅ ) ₇₃ , Hc shows a value that is neither too small nor too large in a temperature range up to about 60 ° C. Therefore, the magnetic bit can be stably held in a normal temperature range in the disk drive, and recording can be performed with a magnetic field generated by the magnetic head. Further, since the change of Hc is gradual, it is easy to control the magnetic field of the magnetic head. Furthermore, since DyFeCo is amorphous, noise due to crystal grains does not occur, and a high-quality reproduced signal can be obtained.

FIG. 8 is a graph showing the temperature dependence of the coercive force (Hc) in Dy ₂₅ (Fe ₆₅ Co ₃₅ ) ₇₅ .

As shown in FIG. 8, the T
_comp is about 60 ° C. Then, in a range from room temperature (25 ° C.) to 60 ° C. which is the maximum temperature in the drive, Hc rises sharply with the temperature rise. If Hc is large, the magnetic bit is thermally stable, but a magnetic head that generates a strong magnetic field for recording is required. At present, it is difficult to realize a magnetic head that generates a magnetic field of 10 kOe or more. Further, it is difficult to control the strength of the recording magnetic field of the magnetic head to an appropriate value in response to a rapid change in Hc due to a temperature change.

From the results shown in FIGS. 7 and 8, T
_{By satisfying comp} ≧ 80 ° C., a disk medium which is thermally stable and has no rapid change in Hc in a practical temperature environment of the magnetic disk can be obtained.

FIG. 9 is a graph showing the dependence of T _{comp on} the Dy addition concentration (x dependence) in Dy _x (Fe ₆₅ Co ₃₅ ) _{1 -x} .

As shown in FIG. 9, the Dy addition concentration was 24
At at%, T _comp = room temperature (25 ° C.). When the concentration of Dy added is 26 at%, T _comp = 8
0 ° C. Therefore, it can be seen that in order to satisfy T _comp ≧ 80 ° C., it is sufficient to satisfy x ≧ compensation composition + 0.2. The compensation composition is a composition for which room temperature is a compensation temperature, and is 0.24 here. This relationship also holds when Tb or Gd is further added as a nonmagnetic material such as Cr or a rare earth metal.

FIG. 10 is a graph showing the temperature dependence of the coercive force (Hc) in Dy ₃₂ (Fe ₆₅ Co ₃₅ ) ₆₈ .

This medium shows the property of Tc <T _comp . Hc at room temperature is as low as 1 kOe, and Hc simply decreases as the temperature increases. Therefore, it is difficult to stably maintain the magnetic bit in a high-temperature environment. Therefore, it is desirable that Tc ≧ T _comp . When the concentration of the rare earth metal exceeds 30 at%, Tc <T _comp , and
It can be said that the coercive force becomes extremely small, which is disadvantageous for high density recording.

FIG. 11 is a graph showing the dependence of Hc on the Dy addition concentration (x dependence) in Dy _x (Fe ₆₅ Co ₃₅ ) _{1 -x} .

As shown in FIG. 11, when the additive concentration of Dy is about 24 at%, Hc has a peak, and in a region higher than that, Hc decreases as the concentration increases.
1 required to keep magnetic data thermally stable
In order to secure Hc of kOe or more, it is desirable from FIG. 11 that the concentration of Dy is 30 at% or less, that is, x ≦ 0.30.

FIG. 12 is a graph showing the dependency of the Curie temperature Tc on the Co addition concentration (y dependency) in Dy ₂₇ (Fe _{1 -y} Co _y ) ₇₃ .

As shown in FIG. 12, the Co concentration increases.
It can be seen that the Curie temperature increases as the temperature increases. Place
Therefore, as shown in the characteristics shown in FIG.
To reduce the variation of Hc with respect to temperature change in the region,
T_comp≤ Tc. Tc <T_compconnection of
If there is, T_compThe magnetism disappears in the following areas,
As shown in FIG. 10, as the temperature increases from room temperature,
Hc decreases. T _compDepends mainly on the rare earth metal concentration.
Therefore, as shown in FIG.
Ascend. Also, as described above, securing a coercive force of 1 kOe.
For this purpose, the Dy concentration must be 30 at% or less.
It is important that the Ty when the Dy concentration is in this range is_compMost
The maximum value is about 150 ° C. from FIG. That is, T
_compTo satisfy ≦ Tc, Tc ≧ 150 ° C.
Is required. FIG. 12 shows that the Co concentration in the transition metal
If the degree is 25 at% or more, that is, y ≧ 0.25,
It satisfies Tc ≧ 150.

[0062]

As described above, the disk medium of the present invention uses an alloy of a rare earth metal and a transition metal as the magnetic recording layer, and satisfies 80 ° C. ≦ T _comp ≦ Tc. It is possible to achieve both good stability and easy recording by the magnetic head. In addition, noise due to crystal grains does not occur due to being amorphous. Therefore, a high recording density of the disk medium can be achieved, and a highly versatile disk medium applicable not only to the magneto-optical disk device but also to the magnetic disk device can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a disk medium of the present invention.

FIG. 2 is a side sectional view of a magnetic head used in the disk drive of the present invention.

FIG. 3 is a sectional view of the magnetic head shown in FIG. 2, taken along line BB.

FIG. 4 is a plan view of the disk device of the present invention.

FIG. 5 is a sectional view of the disk device of the present invention.

FIG. 6 is a view showing a sputtering apparatus.

FIG. 7 is a graph showing temperature dependency of coercive force (Hc) in Dy ₂₇ (Fe ₆₅ Co ₃₅ ) ₇₃ ;

FIG. 8 is a graph showing temperature dependency of coercive force (Hc) in Dy ₂₅ (Fe ₆₅ Co ₃₅ ) ₇₅ .

FIG. 9 shows T _comp in Dy _x (Fe ₆₅ Co ₃₅ ) _1-x .
5 is a graph showing the Dy concentration dependency (x dependency) of Dy.

FIG. 10 is a graph showing temperature dependence of coercive force (Hc) in Dy ₂₇ (Fe ₆₅ Co ₃₅ ) ₇₃ ;

FIG. 11 shows Hc of Dy _x (Fe ₆₅ Co ₃₅ ) _1-x
5 is a graph showing the Dy concentration dependency (x dependency) of Dy.

FIG. 12 is a graph showing Co concentration dependency (y dependency) of Curie temperature Tc in Dy ₂₇ (Fe _{1 -y} Co _y ) ₇₃ .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... NiP layer 3 ... Magnetic recording layer 4 ... Protective layer

Claims (3)

[Claims] 1. A disk medium in which an alloy of a rare earth metal and a transition metal is used as a magnetic recording layer, wherein a compensation temperature is 80 ° C. or higher and a Curie temperature or lower. 2. The magnetic recording layer according to claim 1, wherein said magnetic recording layer is Dy _x (Fe _1-y Co
_y ) _1-x , 0.26 ≦ x ≦ 0.30, 0.25
2. The disk medium according to claim 1, wherein ≤y <1.0. 3. A non-magnetic protective layer having a thickness of 5 to 10 nm is formed on said magnetic recording layer.
A disk medium according to claim 1.