JP2002157793A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium in which regenerative signal quality, especially a jitter characteristic can be improved in a high linear velocity recording and reproduction mode in a reproducing method capable of reproducing a high density recording signal surpassing an optical diffraction limit by detecting magnetic domain wall motion. SOLUTION: In this magnetic recording medium provided at least with a motion layer where a magnetic domain wall moves, a memory layer holding a recording magnetic domain corresponding to information, an interruption layer which is arranged between the motion layer and the memory layer and in which a Curie temperature is lower than those of the both layers, and an interruption auxiliary layer whose Curie temperature is almost equal to that of the interruption layer, the anisotropic energy of the motion layer is set to be larger than that of the interruption auxiliary layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium for recording information according to the arrangement of magnetization of a magnetic material. In particular, DWDD (Domain Wall Displacement
Detection) type magneto-optical recording medium.

[0002]

2. Description of the Related Art Various magnetic recording media have been put into practical use as rewritable recording media. In particular, a magneto-optical recording medium that writes information on magnetic domains in a magnetic thin film using the heat energy of a semiconductor laser and reads this information using a magneto-optical effect is a large-capacity interchangeable medium capable of high-density recording. Expected. In recent years, along with the trend of digitizing moving images, there has been an increasing demand for increasing the recording density of these magnetic recording media to produce larger-capacity recording media.

Generally, the linear recording density of an optical recording medium greatly depends on the laser wavelength of a reproducing optical system and the numerical aperture NA of an objective lens. That is, when the laser wavelength λ of the reproducing optical system and the numerical aperture NA of the objective lens are determined, the beam waist diameter is determined, so that the spatial frequency of a recording pit from which a signal can be reproduced is limited to about 2 NA / λ. Therefore, in order to realize a higher density in a conventional optical disk, it is necessary to shorten the laser wavelength of the reproducing optical system or increase the numerical aperture of the objective lens. However, it is not easy to shorten the laser wavelength due to problems such as the efficiency of the element and heat generation, and if the numerical aperture of the objective lens is increased, the demand for mechanical accuracy becomes strict due to a shallower depth of focus. Problems arise.

For this reason, various so-called super-resolution techniques have been developed for improving the recording density by devising the structure of the recording medium and the reproducing method without changing the laser wavelength or the numerical aperture of the objective lens.

For example, JP-A-3-93058 and JP-A-6-12
No. 4500, after signal recording is performed on a multi-layered recording holding layer having a reproducing layer and a recording holding layer that are magnetically coupled, and after the magnetization direction of the reproducing layer is aligned (Japanese Unexamined Patent Publication No. A signal reproducing method has been proposed in which a magnetization direction of -124500 is in-plane), a laser beam is irradiated and heated to read a signal recorded on the recording holding layer while transferring the signal recorded on the recording holding layer to a heated region of the reproducing layer.

According to this method, the area (aperture) where the transfer temperature heated by this laser is reached and a signal is detected can be limited to a smaller area with respect to the spot diameter of the laser for reproduction. And the signal having a pit period equal to or less than the optical detection limit λ / 2NA can be reproduced.

[0007] The above reproducing method is based on MSR (Magnetically in
duced Super-resolution Readout method). However, this MSR reproduction method has a disadvantage that a signal detection area which is effectively used with respect to a spot diameter of a reproduction laser is reduced, so that a reproduction signal amplitude is greatly reduced and a sufficient reproduction output cannot be obtained. Have. For this reason, the effective signal detection area cannot be made very small with respect to the spot diameter, and in the end the recording density determined by the diffraction limit of the optical system cannot be significantly increased.

Therefore, Japanese Patent Application Laid-Open No. Hei 6-290496 discloses that
The domain wall existing at the boundary of the recording mark is moved to the high temperature side by a temperature gradient, and by detecting this domain wall movement, a signal with a recording density exceeding the resolution of the optical system can be reproduced without reducing the reproduction signal amplitude. A magneto-optical recording medium and a reproducing method therefor have been proposed. This playback method uses DWDD (Domain Wall Displacement Detect
It is called an ion) regeneration method.

As shown in FIG. 4, the magneto-optical recording medium and the reproducing method use the first magnetic layer 40 having a small domain wall coercive force.
01, a second magnetic layer 4002 having a low Curie temperature, and a third magnetic layer 4003 having a large domain wall coercive force. Literature J.
Magn. Soc. Jpn., 22, suppl.No.S2, pp. 47-50 (199
8), the first magnetic layer 4001 functions as a displacement layer (displacement layer) in which domain wall movement occurs during reproduction, and the second magnetic layer 4002 functions as a switching layer (switching layer) for controlling the start position of domain wall movement. Functioning, the third magnetic layer 4003 is a memory layer that holds information
Function as

When a temperature distribution as shown in FIG. 4B is formed on these magnetic film surfaces, a distribution of the domain wall energy density is formed as shown in FIG.
As shown in (d), a domain wall driving force (Equation 1) for moving the domain wall to the high temperature side with low energy is generated.

∂σd / ∂X Equation 1 Here, σd is the domain wall energy of the moving layer, and 4
√ (AK). A is the exchange stiffness constant,
K is the anisotropic energy.

However, at a temperature lower than the Curie temperature of the blocking layer, the magnetic layers are exchange-coupled to each other.
Even if the above-described domain wall driving force acts, domain wall movement does not occur because of the large domain wall coercive force of the memory layer. However,
Since the exchange coupling force (Equation 2) is weakened at the temperature Ts near the Curie temperature of the blocking layer, only the domain wall in the moving layer having a small domain wall coercive force (Equation 3) moves independently to the high temperature side.

Σw / h Equation 2 2MsHw Equation 3 where σw is the interface domain wall energy of the moving layer, h is the thickness of the moving layer, Ms is the saturation magnetization of the moving layer, and Hw is the moving layer's saturation magnetization. Domain wall coercivity.

When the medium is moved relatively to the temperature distribution, the domain wall movement occurs at a time interval corresponding to the spatial interval of the domain wall. Therefore, by detecting the occurrence of the domain wall motion, it becomes possible to reproduce a signal regardless of the resolution of the optical system.

Now, the domain wall movement start temperature Ts is
The frictional force (Equations 2 and 3) that hinders the movement of the domain wall is determined as a threshold temperature at which the domain wall driving force (Equation 1) becomes smaller. When the magnitude relationship between the two is reversed as rapidly as possible before and after the threshold temperature Ts, the domain wall movement start position does not fluctuate and jitter can be suppressed. For this reason, the blocking layer is made of a material having as large anisotropy as possible and a large domain wall energy density so that the exchange coupling force between the moving layer and the memory layer rapidly decreases toward the Curie temperature of the blocking layer. It is better to do.

However, in the three-layer structure of the moving layer, the blocking layer, and the memory layer as described above, there is a problem caused by the large perpendicular magnetic anisotropy of the blocking layer.

Even when the temperature becomes higher than the Curie temperature of the barrier layer, magnetic atoms on the barrier layer side receive a large molecular magnetic field from the barrier layer at the interface between the barrier layer and the barrier layer. Causes spin ordering. Since the blocking layer is essentially made of a material having a large anisotropy, if spin ordering occurs under the influence of a molecular magnetic field, the anisotropy becomes considerably large, and a large domain wall coercive force is induced. Also, taking into account the diffusion of atoms, the anisotropy of the barrier layer near the interface is further increased. Therefore, even if the exchange coupling force with the memory layer sharply decreases, the domain wall coercive force of the barrier layer near this interface is reduced. The remaining problem is that the frictional force that hinders the movement of the domain wall does not decrease sharply, the position where the domain wall movement starts fluctuates, and the jitter increases.

Therefore, Japanese Patent Application Laid-Open No. 12-207791 discloses that the domain wall coercive force is relatively small between the moving layer and the blocking layer as compared with the blocking layer and the memory layer, and that the blocking layer and the Curie temperature are substantially equal. By providing the blocking auxiliary layer made of the same magnetic film, the above-mentioned problem can be solved by the DWD.
A magnetic recording medium using the D reproduction method has been proposed.

[0019]

However, the moving layer, which has been proposed so far, has a frictional force that hinders the movement, that is, a frictional force that hinders the movement of the magnetic domain wall in order to smoothly move the domain wall.
The main focus is on reducing the domain wall coercivity, and such materials include, for example, GdCo, GdFeCo, GdF
e, amorphous rare earth-transition metal alloys such as NdGdFeCo have been used. As a result, the conventional moving layer has a small anisotropic energy and a small domain wall energy, so that the domain wall driving force for moving the domain wall is small. Therefore, if the linear velocity during recording / reproduction is increased to achieve a high transfer rate, there is a problem that jitter characteristics are deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a magnetic recording system capable of obtaining a good jitter characteristic even when the linear velocity during recording / reproduction is increased to achieve a high transfer rate. The purpose is to provide a medium.

[0021]

The magnetic recording medium of the present invention has at least a moving layer in which a domain wall moves, a memory layer holding recording magnetic domains according to information, and a magnetic layer disposed between the moving layer and the memory layer. A barrier layer having a lower Curie temperature than both layers, and a barrier auxiliary layer having a Curie temperature substantially equal to the barrier layer, wherein the anisotropic energy of the moving layer is smaller than the anisotropic energy of the barrier auxiliary layer. It is characterized by being large.

FIG. 1 and FIG. 2 are schematic diagrams of DWDD reproduction signal waveforms for explaining the operation of the magnetic recording medium of the present invention. FIG. 1 shows an example using the magnetic recording medium of the present invention, and FIG. 2 shows an example using the conventional magnetic recording medium. FIG. 3A shows a reproduced signal waveform at a relatively low linear velocity as conventionally used, and FIG. 3B shows a reproduced signal waveform at a relatively low linear velocity in order to achieve a high transfer rate. 5 shows a reproduced signal waveform when the speed is increased. The rising portion of the reproduced signal waveform indicated by the symbol A in the figure is a portion corresponding to the domain wall movement of the moving layer, and the degree of the inclination depends on the domain wall moving speed.

As shown in FIG. 2, in the conventional magnetic recording medium, when the linear velocity increases, the occupancy of the rising portion of the reproduced signal waveform increases, and a rectangular shape unique to DWDD reproduction can be sufficiently obtained. Not. For this reason, it is considered that sufficient reproduction signal quality cannot be obtained and the jitter characteristic deteriorates.

On the other hand, in the magnetic recording medium of the present invention, the moving layer is provided with a magnetic film whose anisotropic energy is larger than that of the blocking auxiliary layer, so that the domain wall energy, that is, the domain wall driving force is appropriate. Big. As a result,
As shown in FIG. 1, since the domain wall movement is performed more quickly than in the prior art, the rise of the reproduced signal waveform is steep, and the reproduced signal waveform does not collapse even at a high linear velocity, and good jitter characteristics can be obtained. Conceivable.

As the material of the moving layer, an amorphous rare earth-transition metal alloy containing at least Dy or Tb element is preferable.

However, if the perpendicular magnetic anisotropy of the moving layer is carelessly increased too much, the balance with the domain wall coercive force will be lost, and the domain wall will not move smoothly in the moving layer.

Therefore, the content of the Dy element in the moving layer is 10 at. % At least 40 at. %
In the following range, the content of the Tb element is 10a in atomic ratio.
t. % At least 30 at. % Is preferable. Also,
In the above magnetic recording medium, the moving layer is stepwise or continuously in the thickness direction, the magnetic recording medium having a structure such that the Curie temperature becomes lower as it approaches the blocking auxiliary layer, Since a domain wall driving force relatively larger than the domain wall coercive force can be applied to the domain wall in the moving layer, the domain wall movement becomes smoother and the reproduction signal characteristics are improved.

Further, by providing a magnetic recording medium having a recording track and having exchange coupling in the film surface direction of the moving layer cut or reduced on both sides of the recording track, a magnetic domain is formed on the track. Information can be recorded as an unclosed domain wall array pattern without substantially forming domain walls on both sides. If the recording pattern in such a state is read while moving the domain wall, the domain wall can be moved without generating / disappearing the side domain wall.
The domain wall movement is stabilized, and the reproduction signal characteristics are further improved.

[0029]

Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a schematic sectional view showing one embodiment of the layer structure of the magnetic recording medium used in the present invention. In this embodiment, an underlayer 3006 on a substrate 3005, a moving layer 3001 in which a domain wall moves during reproduction, and has a larger anisotropic energy than an auxiliary blocking layer described later, and a blocking layer at a temperature near the Curie temperature of the blocking layer described later. In order not to induce a large domain wall coercive force, a Curie temperature substantially equal to that of the blocking layer, a blocking layer described later, a blocking auxiliary layer 3002 having a smaller domain wall coercive force than the memory layer, and a moving layer for controlling the starting position of domain wall movement. And a blocking layer 3 having a lower Curie temperature than the memory layer described later
003, a memory layer 3004 for holding information, and an upper layer 3007 are sequentially stacked.

As the substrate 3005, for example, polycarbonate, acrylic, glass or the like can be used.
Further, the substrate 3005 is formed with irregularities used as recording tracks.

As the underlayer 3006 and the upper layer 3007, for example, SiN, AiN, SiO, ZnS, Mg
A dielectric material such as F or TaO can be used. The material is not necessarily required to be a translucent material unless the movement of the domain wall is optically detected.

The layers other than the magnetic layer are not essential. The order of lamination of the magnetic layers may be reversed. Also, in this configuration,
Further, Al, AlTa, AlTi, AlCr, Cu, P
A thermal property may be adjusted by adding a metal layer made of t, Au, or the like. (Not shown) Further, a protective coat made of a polymer resin may be provided. Alternatively, a substrate after film formation may be attached.

Each of these layers can be formed by, for example, continuous sputtering with a magnetron sputtering apparatus or continuous vapor deposition. In particular, the respective magnetic layers are exchange-coupled to each other by being continuously formed without breaking the vacuum.

In the above medium, each of the magnetic layers 3001 to 3003
004 may be made of various magnetic materials such as a magnetic bubble material and an antiferromagnetic material, in addition to materials generally used for magnetic recording media and magneto-optical recording media.

For example, Pr, Nd, Sm, Eu, Gd,
One or more rare earth metal elements such as Tb, Dy, Ho, Er and the like are 10 to 40 at. %, Fe, C
one or more of iron group elements such as o, Ni, etc.
0 to 60 at. % Of the rare earth-iron group amorphous alloy.

In order to improve corrosion resistance, these alloys are made of Cr, Mn, Cu, Ti, Al, Si, Pt, In.
May be added in small amounts.

Also, a platinum group-iron group periodic structure film such as Pt / Co, Pd / Co, a platinum group-iron group alloy film, Co-Ni
Antiferromagnetic materials such as -O and Fe-Rh alloys, and materials such as magnetic garnets can also be used.

In the case of a heavy rare earth-iron group amorphous alloy, the saturation magnetization can be controlled by the composition ratio between the rare earth element and the iron group element. With a compensating composition, the saturation magnetization at room temperature can be reduced to 0 emu / cc.

The Curie temperature can also be controlled by the composition ratio. To control independently of saturation magnetization,
As the iron group element, a method in which a material in which part of Fe is replaced by Co and the amount of replacement is controlled can be more preferably used. That is, the Fe element 1 at. By replacing% with Co, a Curie temperature rise of about 6 ° C. can be expected. Therefore, the amount of Co to be added is adjusted using this relationship so as to obtain a desired Curie temperature.

On the contrary, it is also possible to lower the Curie temperature by adding a small amount of a nonmagnetic element such as Cr, Ti, or Al.

The Curie temperature can also be controlled by adjusting the composition ratio of two or more rare earth elements.

More specifically, the Curie temperature of the first magnetic layer is 150 to 300 ° C., the second magnetic layer is 100 to 200 ° C., the third magnetic layer is 100 to 200 ° C., and the fourth magnetic layer is 150 to 300 ° C.
It is preferable to adjust the temperature to the range of 50 ° C.

The domain wall coercive force and the domain wall energy density are controlled mainly by selecting material elements and adjusting the composition, but can also be adjusted by the conditions of the underlayer and the film forming conditions such as the sputtering gas pressure.

Specifically, when a rare earth-iron group amorphous alloy is used, Tb and Dy-based materials have high domain wall coercive force and domain wall energy density, and Gd-based materials have a small value.
By including Dy in the moving layer, the anisotropic energy of the moving layer can be increased as compared with the blocking auxiliary layer. Further, these physical property values can be controlled by adding impurities or the like.

When the moving layer and the blocking auxiliary layer are made of a platinum group-iron group periodic structure film or a platinum group-iron group alloy film,
The domain wall coercive force and the domain wall energy density can be adjusted by adjusting the layer thickness ratio and the lamination cycle.

Further, when a material such as an antiferromagnetic material or a magnetic garnet is used, the domain wall coercive force and the domain wall energy density can be adjusted by selecting the material elements, adjusting the composition, and forming conditions.

The recording of the data signal on the magnetic recording medium of the present invention is performed by associating the magnetization orientation of the memory layer with the data signal by magnetic recording or thermomagnetic recording. Thermomagnetic recording involves modulating the external magnetic field while irradiating a laser beam with a power such that the memory layer is above the Curie temperature while moving the medium, or modulating the laser power while applying a magnetic field in a certain direction There is a method to do.

In the latter case, if the intensity of the laser beam is adjusted so that only a predetermined area in the light spot becomes higher than the Curie temperature of the memory layer, a recording magnetic domain smaller than the diameter of the light spot can be formed, and the resolution of the optical system can be improved. The above high-density recording pattern can be formed.

Hereinafter, the present invention will be described in detail with reference to specific examples, but the present invention is not limited to the following examples unless departing from the gist of the present invention.

[0051]

(Example 1) A DC magnetron sputtering apparatus was charged with B-doped Si and Gd, Dy, Tb,
Attach each target of Fe, Co, and Al, fix the polycarbonate substrate on which the guide groove for tracking is formed to the substrate holder, and vacuum the inside of the chamber with a cryopump until a high vacuum of 1 × 10 −5 Pa or less is obtained. Exhausted. While evacuating, Ar gas was introduced into the chamber until the pressure reached 0.5 Pa, and the target was sputtered while rotating the substrate to form each layer.

At the time of forming the SiN layer, N 2 gas is added in addition to Ar gas.
By introducing a gas, DC reactive sputtering was performed to form a film.

First, an SiN layer is formed as an underlayer by 90
nm. Subsequently, (GdDy2
0) The thickness of the FeCoAl layer is 30 nm, the thickness of the GdFeCoAl layer is 10 nm as an auxiliary blocking layer, and the thickness of Tb is
FeAl layer with a thickness of 10 nm, TbFeC as a memory layer
An o-layer was sequentially formed to a thickness of 80 nm. Finally, a 50 nm SiN layer was formed as a protective layer.

Each magnetic layer is composed of Gd, Dy, Tb, Fe, C
The composition ratio was controlled by the ratio of the power applied to each target of o and Al. The composition ratio was adjusted so that each magnetic layer had a composition near the compensation composition. (Strictly speaking, the rare earth element was adjusted to be slightly dominant at room temperature so that the rare earth element and the iron group element were compensated at a temperature near the Curie temperature of the barrier layer, which is the regeneration temperature.) Is adjusted to be about 230 ° C., the Curie temperature of the blocking auxiliary layer and the Curie temperature of the blocking layer are 160 ° C., and the Curie temperature of the memory layer is 310 ° C.
It was adjusted to the extent.

Comparative Example 1 As a comparative example, Dy was added to the moving layer.
A sample similar to that of Example 1 was prepared except that no element was contained.

The dynamic characteristics of the samples of Example 1 and Comparative Example 1 were evaluated using a magneto-optical disk evaluation apparatus equipped with a magnetic head for magnetic field modulation recording, which has been generally used conventionally. . Sample is 1.5m linear velocity
/ Sec and 3.0 m / sec.

At the time of recording, the recording / reproducing laser was set to 4 mW.
By modulating the magnetic field at ± 200 Oe while applying DC current, a pattern of an upward magnetization region and a downward magnetization region corresponding to the modulation of the magnetic field was formed in the cooling process after heating the memory layer to the Curie temperature or higher.

The power Pr of the reproducing laser is set to 1.8 mW.
When the jitter in a tone pattern with a mark length of 0.1 μm was measured, the linear velocity was 1.5 m / sec.
At a linear velocity of 3.0 m / sec, the sample of Comparative Example 1 had a jitter of 4.5 nsec, while the sample of Example 1 had a jitter of 3.5 nsec.

(Example 2) From the sample of Example 1, samples in which the content of the Dy element in the moving layer was variously changed were prepared, and the dynamic characteristics were similarly evaluated. The result is shown in FIG.
Shown in As is clear from FIG. 5, the content of the Dy element in the rare earth element is 10 at. % Or more 4
0 at. %, A minimum jitter value of about 3.5 nsec is obtained at a linear velocity of 3.0 m / sec.
The effect of containing the Dy element on the moving layer was observed.

(Embodiment 3) The material of the moving layer was (GdTb)
A sample similar to that of Example 2 was prepared except that FeCoAl was used, and the dynamic characteristics were similarly evaluated. The result is shown in FIG. As is clear from FIG. 6, Tb occupies the rare earth element.
Element content is 10 at. 30% or more
t. %, A minimum jitter value of about 3.5 nsec was obtained at a linear velocity of 3.0 m / sec, and the effect of the Tb element contained in the moving layer was recognized.

(Example 4) The moving layer was composed of the following two layers and formed sequentially. First, a (GdDy20) FeCoAl layer having a Curie temperature of 260 ° C. with a film thickness of 10 nm is used as a first moving layer, and a Curie temperature of 21 is used as a second moving layer.
A (GdDy20) FeCoAl layer at 0 ° C. is formed to a
Were sequentially formed. Next, a Curie temperature of 1
A GdFeCoAl layer at 60 ° C. was formed to a thickness of 10 nm.

Subsequently, the blocking layer and the memory layer were formed in Example 1.
A film was formed with the same material and the same thickness. The composition ratio was adjusted so that each magnetic layer had a composition near the compensation composition.

The recording / reproducing characteristics of the magneto-optical recording medium of this embodiment were measured by the same method as in the first embodiment.
At 5 m / sec, a jitter of 6.0 nsec was obtained, and at a linear velocity of 3.0 m / sec, 3.2 ns of jitter was obtained.
An ec jitter was obtained, and the effect of lowering the Curie temperature of the moving layer stepwise or continuously in the film thickness direction as approaching the blocking auxiliary layer was recognized.

(Embodiment 5) A tracking servo was applied to the guide groove of the magnetic recording medium of Embodiment 4 to obtain a linear velocity of 1.5 m / m.
While driving the medium in sec, a focused laser beam for recording / reproducing was continuously irradiated at 10 mW, and only the magnetic film on the guide groove was subjected to local annealing. With this process,
The magnetism of the magnetic film on the guide groove was degraded, and the domain wall energy was not accumulated in this portion.

On the lands of this sample, magnetic domains were recorded over the entire land width to form unclosed domain walls. As a result of the reproduction in the same manner as in the first embodiment, the noise at the time of reproduction is reduced, and the linear velocity is set to 5.5 ns at a linear velocity of 1.5 m / sec.
A jitter of 3.0 nsec is obtained at a linear velocity of 3.0 m / sec, and the coupling due to exchange interaction in the film surface direction of the moving layer is cut or reduced on both sides of the recording track. The effect was recognized.

In addition to the examples described above, the magnetic recording medium of the present invention is not limited to the change in the polarization plane due to the magneto-optical effect, and may detect and reproduce another change caused by the movement of the domain wall. The recording film of the magnetic recording medium of the present invention may not be a perpendicular magnetization film as long as it is a magnetic material.

Furthermore, the interface between the magnetic layers does not necessarily have to be sharp and sharp, and the configuration may be such that the characteristics gradually change in the film thickness direction.

[0068]

As described above in detail, according to the present invention, in a reproducing method capable of reproducing a high-density recording signal exceeding the optical diffraction limit by detecting domain wall movement, the present invention provides It is possible to provide a magnetic recording medium capable of improving reproduction signal quality, particularly jitter characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a reproduced signal waveform in a magnetic recording medium of the present invention.

FIG. 2 is a schematic diagram of a reproduction signal waveform in a conventional magnetic recording medium.

FIG. 3 is a schematic sectional view showing one embodiment of a layer configuration in the magnetic recording medium of the present invention.

FIG. 4 is a diagram schematically illustrating the concept of a DWDD playback method.

FIG. 5 is a graph showing the relationship between Dy content and jitter value.

FIG. 6 is a graph showing the relationship between the content of Tb and the jitter value.

[Explanation of symbols]

 3001 moving layer 3002 blocking auxiliary layer 3003 blocking layer 3004 memory layer 3005 substrate 3006 underlayer 3007 upper ground layer 4001 first magnetic layer 4002 second magnetic layer 4003 third magnetic layer

Claims (7)

[Claims] At least a moving layer in which a domain wall moves,
A memory layer that holds a recording magnetic domain according to information, a blocking layer that is disposed between the moving layer and the memory layer and has a lower Curie temperature than the two layers, and a blocking auxiliary layer that has a Curie temperature substantially equal to the blocking layer. A magnetic recording medium comprising: a magnetic recording medium, wherein anisotropic energy of the moving layer is larger than anisotropic energy of the blocking auxiliary layer. 2. The transition layer according to claim 1, wherein the moving layer is made of an amorphous rare earth-transition metal alloy containing at least one of Dy and Tb elements and a Gd element as a rare earth element. Magnetic recording medium. 3. The content of Dy element is 1 in terms of atomic ratio.
0 at. % At least 40 at. %. The magnetic recording medium according to claim 2, wherein 4. The Tb element content is 1 in terms of atomic ratio.
0 at. % At least 30 at. %. The magnetic recording medium according to claim 2, wherein 5. The method according to claim 1, wherein the moving layer is configured such that the Curie temperature decreases stepwise or continuously in the film thickness direction as it approaches the blocking auxiliary layer. Magnetic recording medium. 6. The recording layer according to claim 1, wherein exchange coupling in a film surface direction of the moving layer is cut or reduced at both side portions of the recording track.
6. A magnetic recording medium according to claim 5, wherein 7. The magnetic recording medium according to claim 1, wherein the auxiliary shielding layer has a smaller domain wall coercive force than the shielding layer and the memory layer.