JP2003085702A - Magnetic recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal assist magnetic recording device wherein the limit of thermal fluctuation is overcome, and there are no magnetization losses due to the acceleration of thermal fluctuation. SOLUTION: This magnetic recording device is provided with a nonmagnetic substrate, a function layer made of a magnetic material having Curie temperature Tc FL and a magnetic anisotropic energy density Ku FL, a recording layer made of magnetic particles having Curie temperature Tc RL higher than the Curie temperature Tc FL and a recording temperature Tw and a magnetic anisotropic energy density Ku RL of 5×10<6> erg/cc or higher, and a nonmagnetic material formed therebetween, a heating means for heating the function layer and the recording layer to the recording temperature Tw, and a magnetic recording means for recording signal magnetization by applying a magnetic field to the recording layer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a magnetic recording device.

[0002]

2. Description of the Related Art With the recent increase in processing speed of computers, magnetic storage devices (HDDs) that have information storage and reproduction functions are required to have higher speeds and higher densities. However, it is said that there is a physical limit to high density, and it is being questioned whether or not it is possible to continue to meet this requirement.

A magnetic recording medium in which information is substantially recorded in an HDD has a magnetic layer composed of an aggregate of fine magnetic particles as a recording layer. In order to perform high density recording on this magnetic recording medium, it is necessary to make the magnetic domains recorded in the magnetic layer as small as possible.

Further, in order to be able to separate small magnetic domains, it is necessary that the boundaries of the magnetic domains are smooth.
For that purpose, it is necessary to make the magnetic particles as small as possible. Further, when magnetization reversal is chained between adjacent magnetic particles, the boundaries of magnetic domains are disturbed, so it is necessary to magnetically separate the magnetic particles by a non-magnetic material so that exchange coupling interaction does not work.

Further, in the magnetic head of the HDD, in order to read the magnetic information recorded on the magnetic recording medium, it is necessary to enhance the interaction with the magnetic layer of the magnetic recording medium. For this purpose, it is necessary to reduce the film thickness of the magnetic layer of the magnetic recording medium.

From the above requirements, the volume of the laminated structure of magnetic reversal of the magnetic material constituting the magnetic layer of the magnetic recording medium (substantially equal to the magnetic particles) must be made smaller and smaller.

However, when the magnetization reversal laminated structure is miniaturized, the magnetic anisotropy energy (magnetic anisotropy energy density K _u × volume reversal unit volume V) of the laminated structure becomes smaller than the thermal fluctuation energy. , I can no longer hold the magnetic domain. This is the thermal fluctuation phenomenon, and the physical limit of the recording density, which is mainly caused by this thermal fluctuation phenomenon, is called the thermal fluctuation limit.

As one method for preventing the reversal of magnetization due to thermal fluctuation, it is conceivable to make the magnetic anisotropy energy of the magnetic layer larger than the thermal fluctuation energy.
However, if the magnetic anisotropy energy of the magnetic layer is increased, an inverted magnetic domain is formed (recorded) in the magnetic layer.
Since the coercive force at this time is almost proportional to the magnetic anisotropy energy, the coercive force becomes too large and a magnetic field of about 12 kOe at most is generated. There is a problem that you can not do it.

Thermally assisted magnetic recording has been proposed in order to enable recording with the current recording head even if the magnetic anisotropy energy of the magnetic layer, which is the above problem, is increased.

In heat-assisted magnetic recording, the magnetic layer is locally heated at the time of recording to reduce the magnetic anisotropy energy in the recording area for recording. In heat-assisted recording, even if the magnetic anisotropy energy of the magnetic layer at room temperature is large, it is possible to record with the current head by locally heating only the recording area to reduce the magnetic anisotropy energy in this area. become.

However, in the thermally assisted magnetic recording, the adjacent track portion is heated to some extent during recording, so that the thermal fluctuation is accelerated and the recorded magnetic domain is erased (cross erase).

Further, since the magnetic layer is heated to some extent even when the magnetic field from the recording head disappears immediately after recording, the thermal fluctuation is similarly accelerated and the magnetic domain once formed disappears. There is.

In order to solve these problems, it is necessary to use a material whose change in magnetic anisotropy energy density K _u with temperature is as steep as possible near the recording temperature. That is, during recording, the magnetic anisotropy energy density K _u sharply decreases with increasing temperature and reaches a recordable value, and after the recording, the magnetic anisotropy energy density K _u rapidly increases with heat diffusion.
_It is necessary to increase _u so as to prevent heat fluctuation.

However, a CoCr-based magnetic thin film or CoPt currently being developed as a material having a high coercive force.
Since the temperature change of the magnetic anisotropy energy density K _u of the system magnetic thin film is almost linear, the magnetic anisotropy energy density K _u does not return to the original value so fast with respect to the diffusion rate of heat. Therefore, the present heat-assisted magnetic recording cannot solve the problem of loss of recording magnetization or cross erase after recording.

[0015]

As described above, in the conventional thermally assisted magnetic recording, the temperature change of the magnetic anisotropy energy density K _u of the magnetic material used for the magnetic recording medium is slow, so that the magnetic recording medium is immediately recorded. However, there is a problem in that the magnetic anisotropy energy density K _u does not return to the original value and the recording magnetization disappears or cross erase occurs due to thermal fluctuation.

The present invention has been made in view of the above problems, and does not cause the disappearance of the recording magnetization immediately after recording or the cross erase phenomenon, which is caused by the acceleration of thermal fluctuation during the thermally assisted magnetic recording. The purpose is to provide a device.

[0017]

In order to achieve the above object, the present invention provides a non-magnetic substrate and a Curie temperature T _c ^FL and a magnetic anisotropy energy density K _u ^FL formed on the non-magnetic substrate. And a Curie temperature higher than both the Curie temperature T _c ^FL and the recording temperature Tw which are laminated on the functional layer so as to exert antiferromagnetic exchange coupling interaction with the functional layer. a recording layer made of a nonmagnetic material formed between the magnetic particles and the magnetic particles having a T _c ^RL and 5 × ¹⁰ 6 erg / cc or more magnetic anisotropy energy density _K ^{u R L,} the functional layer and A magnetic recording device comprising: a heating unit that heats the recording layer to the recording temperature Tw; and a magnetic recording unit that records signal magnetization by applying a magnetic field to the recording layer. To.

At this time, it is preferable that the magnetic anisotropy energy density K _u ^FL is less than or equal to the magnetic anisotropy energy density K _u ^RL .

The magnetic anisotropy energy density K _u
^FL > the magnetic anisotropy energy density K _u ^RL × 0.1
Is preferred.

The magnetic anisotropy energy density K _u ^RL at the recording temperature Tw is preferably larger than ¼ of the anisotropy energy density K _u ^RL at room temperature.

The Curie temperature T_c ^FLIn
The magnetic anisotropy energy density K_u ^RLAt room temperature
Magnetic anisotropy energy density K_u ^RLGreater than 1/4 of
It is preferable that

Further, it is preferable to have a nonmagnetic intermediate layer having a thickness of 5 nm or less between the recording layer and the functional layer.

The non-magnetic intermediate layer has at least R
u, Re, Rh, Ir, Tc, Au, Ag, Cu, S
It is preferably made of a material selected from i, Fe, Ni, Pt, Pd, Cr, Mn, Al, a semiconductor, and a semiconductor doped with a magnetic material.

Further, according to the present invention, a nonmagnetic substrate is formed on the nonmagnetic substrate, and the amount of magnetization at room temperature is the recording temperature T.
a functional layer made of a ferrimagnetic material having a magnetization amount larger than that of w, magnetic particles laminated on the functional layer so as to exert a ferromagnetic exchange coupling interaction with the functional layer at room temperature, and formed between the magnetic particles. A recording layer made of a non-magnetic material,
A magnetic recording device comprising: heating means for heating the functional layer and the recording layer to the recording temperature Tw; and magnetic recording means for recording signal magnetization by applying a magnetic field to the recording layer. provide.

At this time, it is preferable that the functional layer is made of a rare earth element and a transition metal alloy.

In addition, a laminated structure in which the functional layer includes a first magnetic layer and a second magnetic layer that is antiferromagnetically exchange-coupled with the first magnetic layer is laminated a plurality of times to form the first magnetic layer. It is preferable that the body layer and the second magnetic layer have different Curie temperatures.

Further, it is preferable that the laminated structure including the functional layer and the recording layer is laminated plural times.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 shows an outline of a magnetic disk device using a rotary actuator.

As shown in FIG. 1, a disk 101, which is a magnetic storage medium, is mounted on a spindle 110 and rotated at a predetermined rotation speed. A recording head 1 equipped with a magnetic recording / reproducing element and a heating means for recording / reproducing information while floating or in contact with the disk 101 is provided. The recording head 1 includes a thin plate suspension 50.
It is attached to the tip of. Here, as the magnetic recording generating element, one made of permalloy, Fe or Fe alloy can be used. The magnetic field is 5 kOe to 6
It is sufficient if it is about kOe.

The suspension 50 is connected to one end of an actuator arm 102 having a bobbin portion for holding a drive coil (not shown). On the other hand, the other end of the actuator arm 102 is provided with a voice coil motor 120 which is a kind of linear motor.

The voice coil motor 120 is composed of a drive coil (not shown) wound around the bobbin of the actuator arm 102, and a magnetic circuit composed of a permanent magnet and a facing yoke which are arranged so as to face each other so as to sandwich the coil. ing.

The actuator arm 102 has a fixed shaft 1
It is held by a ball bearing (not shown) provided at 30, and can be freely rotated and rocked by the voice coil motor 120. These configurations are the case 1
It is located in 00.

FIG. 2 is a cross-sectional view of the recording head 1 and the disk 101 which is the magnetic recording medium shown in FIG. 1 when enlarged.

As shown in FIG. 2, a disk 101, which is a magnetic recording medium, has a non-magnetic substrate 13, a functional layer 12 formed thereon, a recording layer 11 formed thereon, and a recording layer 11 formed thereon. The formed protective layer 14 is provided.

A circular hard substrate can be used as the non-magnetic substrate 13. As the material of the substrate 13, a non-magnetic material such as metal, glass or ceramics can be used.

The recording layer 11 contains magnetic particles and a non-magnetic material formed between them. As the material of the magnetic particles present in the recording layer 11, the saturation magnetization Is is large,
In addition, those having large magnetic anisotropy are suitable. From this viewpoint, examples of the magnetic metal material of the magnetic particles include Co, Pt,
It is preferable to use at least one selected from the group consisting of Sm, Fe, Ni, Cr, Mn, Bi and Al, and alloys of these metals.

Among these, Co-based alloys having a large crystal magnetic anisotropy, particularly those based on CoPt, SmCo and CoCr, and ordered alloys such as FePt and CoPt are more preferable. Specifically, CoCr, CoPt, CoCr
Ta, CoCrPt, CoCrTaPt, Fe ₆₀ Pt
_{60, Fe 60 Pd 60, Co} 3 Pt 1 , and the like. In addition to these, TbFe, TbFeCo, TbC
o, GdTbFeCo, GdDyFeCo, NdFeC
Examples thereof include alloys of rare earth elements such as o and NdTbFeCo and transition metals.

The recording layer 11 may be a multilayer film (Co / Pt, Co / Pd, etc.) of a magnetic layer and a noble metal layer. Further, as the recording layer 11, a semimetal such as PtMnSb can be used. The recording layer 11 can be widely selected from magnetic oxides such as Co ferrite and Ba ferrite.

For the purpose of controlling the magnetic characteristics of the magnetic fine particles contained in the recording layer 11, the above magnetic material is further supplemented with Fe and Ni.
It may be alloyed with at least one or more elements selected from In addition, additives such as Cr, Nb, V and T for improving magnetic properties are added to these metals or alloys.
An element such as a, Ti, W, Hf, Cr, In, Si, or B, or a compound of these elements and at least one element selected from oxygen, nitrogen, carbon, and hydrogen may be added.

The magnetic anisotropy of the recording layer 11 may be perpendicular magnetic anisotropy, in-plane magnetic anisotropy or a mixture thereof.

The thickness of the recording layer 11 is not particularly limited, but in order to realize high density recording, it is preferably 100 nm or less, more preferably 50 nm or less, further preferably 20 nm or less. When the thickness is 0.5 nm or less, it is difficult to form a thin film, which is not preferable.

As a method of forming a non-magnetic material between the magnetic particles contained in the recording layer 11 to divide it, Cr, Ta and B are used.
Non-magnetic element such as S, oxide represented by SiO ₂ , S
There is a method of adding a non-magnetic material such as a nitride typified by i ₂ N ₃ or the like to cause precipitation between grains.

Further, a non-magnetic material may be formed between the magnetic particles by artificial processing using a technique such as lithography used for semiconductors. In addition, PS that self-organizes
A non-magnetic material may be formed between the magnetic particles by a self-assembly process using a diblock copolymer such as PMMA as a mask. Further, a non-magnetic material may be formed between the magnetic particles by processing such as particle beam irradiation.

The functional layer 12 may be made of any magnetic material. The magnetic anisotropy may be perpendicular magnetic anisotropy, in-plane magnetic anisotropy or a mixture thereof.

The thickness of the functional layer 12 is also not particularly limited, but 1
It is not preferable that the thickness is 000 nm or more because it takes time to form and characteristics deterioration and peeling easily occur due to film stress. If the thickness is 0.1 nm or less, a thin film cannot be substantially formed, which is not preferable. The requirements that the functional layer must satisfy as a magnetic substance are the same as those of the recording layer.

The exchange coupling interaction between the functional layer 12 and the recording layer 11 is caused by forming the functional layer 12 in a general medium manufacturing process by a sputtering method or the like, and continuously forming the recording layer 11 without breaking the vacuum. It can be realized by forming a film. However, at this time, when the spin directions of the functional layer 12 and the recording layer 11 are antiparallel, it is necessary to set the energy to the lowest. This is an antiferromagnetic exchange coupling interaction.

The structure exhibiting the antiferromagnetic exchange coupling interaction can be realized by controlling the state of the interface between the recording layer 11 and the functional layer 12. For example, examples thereof include a region having a partially changed magnetism, a surface modification layer or a physical / chemical adsorption layer formed, and the bonding state of the interface being different depending on the micro portion.

In any case, even if the gap between the recording layer 11 and the functional layer 12 is theoretically several nm apart, the antiferromagnetic exchange coupling interaction extends, and therefore the antiferromagnetic exchange coupling interaction acts. A non-magnetic layer may be provided between the functional layer 12 and the recording layer 11 as long as it is present.

The antiferromagnetic exchange coupling force can also be controlled by inserting another magnetic film between the functional layer 12 and the recording layer 11. Therefore, unless the action of the present invention is impaired, the functional layer and the recording layer are not affected. A plurality of magnetic layers may be present between them.

Although the laminated structure of the functional layer 12 and the recording layer 11 can achieve the effect of the magnetic recording medium of the present invention, the protective layer 14 is formed on the recording layer 11 if necessary. Good. As the protective layer 14, a thin film made of C, SiO ₂ or the like can be used.

An underlayer can be used between the substrate 13 and the functional layer 12. By using the underlayer, controllability of various characteristics of the functional layer 12 and the recording layer 11 can be improved. The underlayer may be magnetic or non-magnetic. The thickness of the underlayer is not particularly limited, but if it is thicker than 500 nm, the manufacturing cost increases, which is not preferable.

Efficient recording on a magnetic thin film by magnetically coupling the underlying layer with a magnetic domain in the magnetic material of the recording layer 11 or the recording head 1 through exchange interaction or magnetostatic interaction. And replay can be performed. For example, when the recording layer 11 is a perpendicular magnetization film, high density recording can be performed by using a soft magnetic film as an underlayer and recording with a single magnetic pole head. In this case, recording can be performed on the recording medium 101 even if the magnetic field of the recording head is smaller.

When the recording layer 11 is an in-plane magnetized film, a soft magnetic layer is provided above or below the recording layer 11 and a magnetic field having a strength that saturates the soft magnetic layer is applied during reproduction,
High-density recording is possible, and thermal fluctuation resistance is also improved.

By using a nonmagnetic material for the underlayer, it is possible to control the crystal structure of the magnetic portion and the nonmagnetic portion. Further, it is possible to prevent impurities from the substrate 13 from mixing into the functional layer 12 and the recording layer 11. At this time, a thin film having a small or small lattice spacing may be used as the base layer.

Further, by using an underlayer having a lattice spacing close to the lattice spacing of the crystal orientation of the magnetic portion, it is possible to control the crystalline state of the magnetic portion.

Further, for example, the crystallinity or amorphousness of the magnetic portion or the non-magnetic portion may be controlled by using an amorphous underlayer having a certain surface energy.

Further, an underlayer may be provided below the underlayer. In that case, since the functions can be shared, the effect increases. For example, a seed layer having a small grain size is provided on the substrate 13 for the purpose of reducing the crystal grains of the recording layer 11,
A base layer for controlling the crystallinity of the recording layer 11 can be provided thereon.

The magnetic and nonmagnetic underlayers may have the same function. That is, there may be a magnetic underlayer that controls the crystallinity of the magnetic part. In this case, the effect on the recording or reproducing characteristics and the effect on the crystallinity are synergistic, so that it is preferable to each case.

The base layer is an ion plating,
It may be a surface modification layer of the substrate 13 which is formed by doping in an atmosphere gas, neutron irradiation or the like. in this case,
It is preferable for making a magnetic recording medium because it does not require a process of depositing a thin film.

The recording head 1 is adapted to be able to apply a local magnetic field directly below it and locally heat it. Then, by applying a local magnetic field, a fine magnetization reversal portion can be formed in the recording layer 11.

The means for heating may be either one that heats the entire surface of the magnetic recording medium disk 101, or one that heats only the local portion, as long as the portion reaching the recording temperature is local. In general, it is preferable to locally heat the medium so that most of the medium is kept at room temperature or at a temperature of room temperature or lower in consideration of recording retention characteristics (archiving characteristics) and power consumption.

In order to perform high-speed and local heating, a laser such as that used in an optical disk is used, induction heating is performed, or a probe heated by a heating wire or the like is brought closer to or farther from it, or A device that emits an electron beam can be considered.

In order to perform more localized heating,
A method of narrowing the laser light on the medium surface using a lens or the like, a method of making the laser light a near-field light by using a minute aperture or a solid immersion lens, or producing a fine antenna at the probe tip. A method of performing induction heating, a method of sharpening the shape of the medium facing portion of the heating probe as much as possible or a method of further shortening the approaching distance, a method of sharpening the shape of the medium facing portion of the electron beam emitting probe as much as possible, etc. Can be mentioned. The heating device using these methods may be on the recording surface side of the medium or on the opposite surface side.

The means for applying the magnetic field existing in the recording head 1 may be one having a magnetic circuit consisting of an induction coil and a magnetic pole on the end face of a flying slider as used in a normal HDD. Further, a permanent magnet may be installed, or a magnetic layer may be further added to the magnetic recording medium to generate an instantaneous and local magnetic field by the temperature distribution or the magnetization distribution by light irradiation. Alternatively, a leakage magnetic field generated from the magnetic layer itself that records information may be used.

When a permanent magnet is used as the recording head, the distance between the permanent magnet and the medium is made variable, and recording can be performed by moving the magnet closer, and recording is not performed when the distance is increased. When overwriting what has been recorded once, the magnet may be reversed and the same operation may be performed. Further, by making the magnet fine, high density recording becomes possible. Further, the speed can be increased by moving the piezoelectric element or the like at high speed.

In the present invention, the same method as that of the conventional magnetic recording apparatus can be used to read the retained magnetic recording information. That is, the leakage magnetic field from the magnetic recording medium 101 is detected by the magnetic reproducing head 1 using the giant magnetoresistive effect. That is, since the recorded information can be read without light irradiation, compatibility with the conventional reading system is ensured.

The Curie temperature Tc of the magnetic material of the recording layer 11 and the functional layer 12 can be examined by the temperature dependence of the magnetization M or the coercive force Hc. When the magnetic characteristics are measured by VSM or the like, it is necessary to keep the heating state for about 10 minutes, and the rate of temperature rise cannot be shortened, so the sample is kept at that temperature for about 1 hour.

In the case of a magnetic thin film, there is a possibility that irreversible fine structure change may occur due to this high temperature holding, and accurate magnetic property evaluation may not be possible. In the case of amorphous rare earths and transition metal alloys used as magneto-optical recording media, such changes are relatively unlikely to occur, but CoCrPt-based media used as HDD media, etc. It may occur at about ℃.

Even in such a case, the Curie temperature Tc can be estimated. That is, the change in the magnetic properties from room temperature or lower to the temperature at which the structural change occurs may be extrapolated to the high temperature side.

Further, the Curie temperature Tc in the magnetic recording apparatus according to the present invention is required to be a temperature at which the magnetic anisotropy energy density K _u becomes substantially small. Hc value is 1 at room temperature
It is enough if the estimation can be about / 20.

Further, the magnetic anisotropy energy density K _u ^RL of the recording layer 11 must be 5 × 10 ⁶ erg / cc or more. If it is smaller than this, the merit of the thermally assisted magnetic recording cannot be obtained.

FIG. 3 shows the magnetic anisotropy energy density K _u ^RL of the recording layer 11, the magnetic anisotropy energy density K _u ^{FL of} the functional layer 12, and the reversal magnetic field H _{c of the} entire magnetic recording medium.
^total , the recording magnetic field H _w applied from the recording head 1
The change with temperature is schematically shown.

As shown in FIG. 3, the Curie of the functional layer 12 is
Temperature T_c ^FLIs the Curie temperature T of the recording layer 11._c ^RLYo
It is low. Further, the magnetic anisotropy energy density of the functional layer 12 is
Degree K _u ^FLIs the magnetic anisotropy energy density of the recording layer 11.
K_u ^RLSmaller than that, and changes more rapidly with temperature changes.
It has become.

The functional layer 12 and the recording layer 11 are antiferromagnetically exchange-coupled. Therefore, the reversal magnetic field H _c ^total for reversing the synthesized magnetization is not proportional to the magnetic anisotropy density K _u ^RL of the recording layer 11 in the temperature range equal to or lower than the Curie temperature T _c ^FL of the functional layer 12, and changes in temperature. It changes sharply and has a sufficiently large value. In this temperature range, there is no problem of inversion due to the thermal fluctuation phenomenon.

When the medium temperature rises above the Curie temperature T _c ^FL of the functional layer 12, the magnetic anisotropy density K _{u of the} functional layer 12 is increased.
^FL becomes 0, and the magnetic anisotropy density K _u ^RL of the recording layer 11
The ^switching field H _c ^total is determined only by Therefore, the recording temperature Tw is set to the Curie temperature T _{c of the} functional layer 12.
The recording magnetic field H of the recording head 1 is made larger than ^FL.
It can also be inverted by w.

By doing so, it is possible to solve the problem of loss of recording magnetization and cross erase immediately after recording without making the temperature change of the magnetic anisotropy energy density Ku steep even if the thermal diffusion is gentle.

Thermally assisted magnetic recording utilizing this characteristic will be described in detail.

FIG. 4 is a cross-sectional structure of the magnetic recording medium, schematically showing the state of magnetization reversal in the recording layer 11 and the functional layer 12. Reference numeral 31 is a magnetic particle, and the arrow therein indicates the direction of magnetization. The length of the arrow represents the magnitude of the magnetization or switching field. Reference numeral 32 is a non-magnetic material between the magnetic particles 31. The functional layer 12 also has the same structure as the recording layer 11 and is composed of magnetic particles and a non-magnetic material that divides the magnetic particles.
In addition to this structure, for example, a continuous film or a (three-dimensional) granular structure may be used. Here, for simplicity, a case of a perpendicular magnetic recording medium will be described as an example.
The description given here can be applied as it is to the case of the in-plane medium or the mixture of both.

The functional layer 12 and the recording layer 11 are antiferromagnetic exchange coupled.
Their magnetization is opposite to that of the recording layer 11.
is there. Therefore, the total amount of magnetization of the recording medium is
The amount of magnetization is smaller than that of a single magnetic field.
growing. Magnetic anisotropy energy density K_uAgainst
Reversal magnetic field, that is, anisotropic magnetic field H_kIs H_k= 2K _u
/ Ms. Ms is saturation magnetization.

First, as shown in FIG. 4A, all the magnetizations of the recording layer 11 are set downward in the initial state. This state is the state at room temperature Ta before application of heat and application of a magnetic field. Upward magnetization is developed in the functional layer 12 by antiferromagnetic exchange coupling interaction with the recording layer 11, and antiferromagnetic exchange coupling is performed with the magnetization of the recording layer 11, and the coercive force thereof is large.

In this state, since the heating is not performed, the magnetization does not disappear due to thermal fluctuation. This state is the state at room temperature Ta in FIG. The reversal magnetic field H _c ^{total at} this time is determined by the magnetic anisotropy energy density K _u ^FL of the functional layer 12 and the recording layer 1.
It is proportional to the value when the magnetic anisotropy energy density K _u ^RL of 1 is synthesized.

Next, as shown in FIG. 4B, only the area shown by the arrow 34 is heated by the heat applying means incorporated in the recording head (reference numeral 1 in FIG. 2). As shown in FIG. 3, as the substrate temperature rises from the room temperature Ta to the recording temperature Tw by applying heat, the reversal magnetic field H _c ^total sharply decreases. This is because the Curie temperature T _c ^FL of the functional layer 12 is lower than that of the recording layer 12, and the magnetic anisotropy energy density K _u ^FL drops sharply. In this way, the state immediately before recording is performed.

Next, as shown in FIG. 4C, a downward magnetic field from the recording head (reference numeral 1 in FIG. 2) is applied to form a recording magnetic domain having a downward spin. The spin relationship between the recording layer 11 and the functional layer 12 is reversed in the opposite direction to the surroundings while keeping the same spin relationship. As shown in FIG. 3, at the recording temperature Tw, the reversal magnetic field H _c ^total becomes lower than the recording magnetic field H _w of the recording head 1, so that the spin can be easily reversed. Here, the recording temperature Tw is the Curie temperature T of the functional layer 12.
It may be higher than _c ^{FL and} the magnetization of the functional layer 12 may disappear.

Next, as shown in FIG. 4D, the heat application is stopped after the recording domain with the downward spin is formed. By doing so, when the temperature returns to room temperature Ta as shown in FIG. 3, the magnetization of the functional layer 12 rapidly increases. This causes the reversal magnetic field H
_c ^total rapidly increases.

As described above, according to the present invention, magnetic recording can be performed on a recording layer having a large magnetic anisotropy energy density Ku which cannot be recorded at room temperature.

Further, according to the present invention, since the situation in which recording can be performed is brought about by the change in the magnetic characteristics of the functional layer having a low Curie temperature, the magnetism of the recording layer itself does not change much from room temperature to the recording temperature. Therefore, acceleration of thermal fluctuation, which is a problem of conventional heat-assisted magnetic recording, is less likely to occur.

In the present invention, the magnitude relationship between the magnetic anisotropy energy density K _u ^RL of the recording layer 11 and the magnetic anisotropy energy density K _u ^FL of the functional layer 12 at room temperature is basically arbitrary. However, in order to realize a higher density magnetic recording device, the magnetic anisotropy energy K _u ^FL of the functional layer 12 at room temperature should be equal to or lower than the magnetic anisotropy energy density K _u ^RL of the recording layer 11. . Further, the recording layer 11 and the functional layer 12 may have the same magnetic anisotropic energy density.

In the present invention, it is preferable that the magnetic anisotropy energy density K _u ^FL of the functional layer 12> the magnetic anisotropy energy density K _u ^{RL of the} recording layer 11 × 0.1. As described above, the magnetic anisotropy energy density K _u ^FL of the functional layer 12 is preferably equal to or less than the magnetic anisotropy energy density K _u ^RL of the recording layer 11. However, the magnetic anisotropy energy density K _u ^FL of the functional layer 12 does not have to be small.

The present inventors investigated the characteristics of the effective magnetic anisotropy energy density K _{u of} the multilayer film with ferromagnetic exchange coupling and antiferromagnetic exchange coupling, and as a result, the following findings were obtained. I found it.

That is, when the first layer and the second layer are bound with the exchange coupling energy areal density σ, the magnetic anisotropy energy density as the overall thermal fluctuation resistance is σ / (2t ₂ K _u2) <in the case of _{1, t 1 K u1 + σ} -σ
^{If 2} / (4t ₂ K _u2 ) σ / (2t ₂ K _u2 )> 1, then t ₁ K _u1 + t ₂ K
_u2 .

Here, t ₁ and t ₂ are the film thicknesses of the first layer and the second layer, respectively, and K _u1 and K _u2 are the magnetic anisotropy energy densities of the first layer and the second layer, respectively. .

In all cases, the thermal fluctuation resistance tK _u as a whole is increasing. However, the average across the membrane is
As can be seen by dividing by (t ₁ + t ₂ ), K _u2 is smaller than K _{u 1} and the effective magnetic anisotropy energy density is reduced.

Since the medium must be thinned for higher density, this is disadvantageous as compared with the case where the material of _Ku1 has the same thickness.

Therefore, the magnetic anisotropy energy density K _u ^FL of the functional layer 12 is preferably as large as possible within a range smaller than the magnetic anisotropy energy density K _u ^RL of the recording layer 11. As a result of detailed experiments and examinations, specifically, functional layer 1
It was found that the relationship of the magnetic anisotropy energy density K _u ^{FL of 2} > the magnetic anisotropy energy density K _u ^RL × 0.1 of the recording layer 11 is sufficient.

In the present invention, the magnetic anisotropy energy density K _u ^RL of the recording layer 11 at the recording temperature Tw is the magnetic anisotropy energy density K of the recording layer 11 at room temperature.
be larger than 1/4 of _u ^{R L.}

The greatest feature of the magnetic recording apparatus according to the present invention is the suppression of the thermal fluctuation acceleration phenomenon. Specifically, recording is performed before the thermal fluctuation of the recording layer 11 is accelerated by utilizing the change of the entire switching magnetic field due to the change of the magnetic characteristic of the functional layer 12. That is, the recording is performed at a temperature sufficiently lower than the Curie temperature of the recording layer 11.

As a result of the inventors' own research, when thermally assisted magnetic recording is performed on a normal single-layer film, the thermal fluctuation acceleration phenomenon can be avoided when the magnetic anisotropy energy density at room temperature is about half. It was found that the temperature was up to. However, this conclusion contains assumptions for simplicity and is found to give an overestimation of thermal fluctuation acceleration. Actually, since a complicated phenomenon involving a change in temperature in the nanometer region on the medium and a spatial distribution of magnetic characteristics accompanying it occurs, accurate analysis cannot be performed unless first-principles simulation is used. As a result of performing a detailed experiment in consideration of these things, the inventors have found that the magnetic anisotropy energy density K _u of the recording layer 11 at room temperature.
It has been discovered that the effect of the thermal fluctuation acceleration phenomenon can be suppressed by measures such as improving the temperature response if heating is performed to a value of the magnetic anisotropy energy density to 1/4 of the ^RL .

That is, the recording layer 11 at the recording temperature Tw
If the magnetic anisotropy energy density K _u ^{R L} is greater than 1/4 of the value at room temperature of can heat-assisted magnetic recording with reduced thermal fluctuation acceleration. At this time, there is no deterioration immediately after recording, and the cross-erase does not occur because the thermal fluctuation acceleration does not occur in the adjacent tracks. Further, the magnetic field application area of the recording head (AB of the recording magnetic pole is approximately
Since the reversal magnetic field in a region wider than the (S-plane region) can be set to be equal to or less than the recording magnetic field, there is also an advantage that the recorded magnetic domain can be a rectangle that is not affected by the isotherm.

This condition is only for suppressing thermal fluctuation acceleration, and the temperature response is extremely high due to the system which allows a certain degree of deterioration or the system which employs the auxiliary magnetic field application immediately after recording, and the super-quick refrigerant structure. It is not necessary to use it for fast systems.

In order to enable recording at a lower temperature, it is preferable that the recording layer 11 itself is a material having a high magnetic anisotropic energy density K _u ^RL and a low coercive force. To do so, the saturation magnetization Ms of the recording layer 11 should be large. However, basically, the magnetic anisotropy energy density K _u
^{The RL} and the saturation magnetization Ms are values specific to the material and cannot be controlled so much.

Therefore, another layer is ferromagnetically exchange-coupled to the recording layer 11.
It can be realized by combining them. That is,
Another material with a high magnetic anisotropy energy density
By exchanging and coupling the second recording layer to the recording layer 11,
Saturation when the recording layer 11 and the second recording layer are regarded as one body
The magnetization Ms can be increased, resulting in high magnetism.
Anisotropy energy density K_u ^RLAnd low coercive force
Wear. In this case, the magnetic anisotropy energy density of the second recording layer
The degree is the magnetic anisotropy energy density K of the recording layer 11. _u ^RLHo
It doesn't have to be expensive.

As such a material system, for example, in the case of a perpendicular magnetic recording medium, a so-called artificial lattice medium in which Co layers having a thickness of about 1 nm and Pt layers and Pd layers are alternately laminated can be used. In this medium, the thinner the Co layer is, the higher the magnetic anisotropy energy density can be.
When the layer has a thickness of 0.25 nm and the Pt layer has a thickness of 0.5 nm, the magnetic anisotropy energy density of 10 ⁷ erg / cc is 5
Ms of about 00 emu / cc can be obtained.

[0104] In the present invention, the magnetic anisotropy energy density _K ^{u RL} of the recording layer 11 in the Curie temperature _T ^{c FL} of the functional layer 11, the magnetic anisotropy energy density _K ^{u RL} of the recording layer 11 at room temperature It is preferably larger than 1/4.

The temperature change (reduction) of the coercive force Hc larger than the recording layer 11 originally has is obtained in the functional layer 1.
2 is in the temperature range having magnetism. That is, the largest decrease in coercive force Hc from room temperature (relative increase in saturation magnetization Ms) is obtained at a temperature equal to or lower than the Curie temperature T _c ^FL of the functional layer 11.

The magnitude of the coercive force at room temperature depends on the magnetism at room temperature.
Meaning less demagnetization, and has a great effect on reducing the demagnetizing field
Means that. Therefore, the recording operation is performed by the function layer 12 queue.
Lee temperature T_c ^FLIf it is done in the vicinity, the demagnetizing field reducing effect will be great.
This is preferable because it can be reduced. From the above discussion, heat fluctuates
In order to suppress the acceleration phenomenon, the recording temperature is set to the magnetic value of the recording layer 11.
Anisotropy energy density K_u ^RLBecomes 1/4 of the room temperature value
System that has both effects.
To obtain the system, the Curie temperature T of the recording layer 12 _c ^FLTo
Magnetic anisotropy energy density K of the recording layer 11 in the_u ^RL
Is the magnetic anisotropy energy density of the recording layer 11 at room temperature
K_u ^RLIt is preferably larger than 1/4 of the above.

This condition is a condition for suppressing thermal fluctuation acceleration and reducing the influence of the demagnetizing field, and it is not necessary to use it for a system that does not require it. Whether to adopt this condition depends on the design of the system used.

In the magnetic recording device according to the present invention, a nonmagnetic intermediate layer having a thickness of 5 nm or less may be formed between the recording layer 11 and the functional layer 12.

In the present invention, antiferromagnetic exchange coupling can be realized by controlling the interface between the recording layer 11 and the functional layer 12, but as another method, the recording layer 11 and the functional layer 1 can be used.
It was revealed by the experiments of the inventors that it can be realized by forming a non-magnetic intermediate layer having a thickness of 5 nm or less between the two. It has been found that the exchange coupling between the recording layer 11 and the functional layer 12 acts at a distance within a range not exceeding 5 nm, and the exchange coupling force can be controlled at that distance. This distance varies depending on the material used, the magnetic / mechanical / chemical state of the interface, the film forming method, the film forming conditions, etc., and cannot be uniquely defined here.

Further, in the present invention, in order to keep the distance between the recording layer 11 and the functional layer 12 under control, an intermediate layer made of a non-magnetic material may be inserted therebetween.

The inventors have found that the non-magnetic intermediate layer contains at least Ru, Re, Rh, Ir, Tc, Au, Ag,
Cu, Si, Fe, Ni, Pt, Pd, Cr, Mn, A
It has been found that a large exchange coupling energy can be obtained when the material is selected from l.

In the case of the magnetic recording apparatus according to the present invention, the necessary condition is that the thermal fluctuation acceleration is small and the reversal magnetic field is small at the recording temperature. There are various conditions for realizing this, and one of them is that the exchange coupling energy is large. This has an advantage that a recording layer having a larger magnetic anisotropy energy density, which can increase the magnetic anisotropy energy density of the functional layer 12, can be used. However, it is not an essential condition that the exchange coupling energy is large, it can be controlled by another parameter, and it may be small depending on the system. In that case, the range of selection of the intermediate layer material is increased, which is preferable.

Further, the inventors have obtained a large exchange coupling energy and a sharp temperature change of the switching field by selecting the nonmagnetic intermediate layer from a semiconductor and a material obtained by doping a semiconductor with a magnetic material. I found that
The reason why a large exchange coupling energy is obtained is not clear. Regarding the abrupt temperature change of the switching field, when the intermediate layer is a semiconductor, the number of electrons (carriers) is considered to be responsible for the exchange coupling interaction between the recording layer 11 and the functional layer 12. This is probably because the decrease in the exchange coupling energy with respect to temperature decreased due to the increase. When a semiconductor is doped with a magnetic material, the effect of increasing the exchange coupling energy is further obtained. Of course, it is not always necessary to use these semiconductor intermediate layers for a system where the influence of the demagnetizing field is small in the first place.

Next, an example in which a magnetic recording device having the cross-sectional structure shown in FIG. 2 is manufactured will be shown.

First, a Ti seed layer (not shown) having a thickness of 10 nm and a Pt underlayer (not shown) having a thickness of 20 nm are formed on a 2.5-inch glass substrate 13 by a sputtering method. Next, a functional layer 12 having five stacked layers of a Co layer having a thickness of 0.32 nm and a Pt layer having a thickness of 0.78 nm is formed thereon by a sputtering method.

Next, a recording layer 11 having (Co ₈₀ Pt ₂₀ ) Ta ₆ as a magnetic substance and SiO ₂ as a non-magnetic substance between them is formed on the functional layer 12 by a sputtering method with a thickness of 10 nm. Next, a protective layer 14 made of C is laminated on the recording layer 12 by a sputtering method with a thickness of 3 nm, and then a lubricant is applied.

The functional layer 12 has a laminated structure composed of a Co layer having a thickness of 0.32 nm and a Pt layer having a thickness of 0.78 nm.
This is a so-called artificial lattice in which this laminated structure is repeated 5 times. Between the functional layer 12 and the recording layer 11, RF 100 W sputter etching treatment is performed in an atmosphere of Ar and N _{2 of} 0.5 Pa.

Next, when the fine structure of the recording layer 11 was analyzed by using a TEM, columnar magnetic crystal grains (diameter of about 9 nm) mainly made of CoPt were separated by a non-magnetic substance made of amorphous SiO _2. It had a structure. Ta could not be analyzed by this analysis.

The magnetic characteristics of the recording layer 11 alone are perpendicular to each other.
Has a main easy axis in the direction, VSM measurement and magnetic
Magnetic anisotropy energy density K from Luk measurement_u ^RL= 8 x
10 ⁶It was estimated to be erg / cc. Also, the key
Curie temperature T_c ^RLWas estimated to be about 800K.

Similarly, the magnetic characteristics of the functional layer 12 alone are such that the magnetic anisotropy energy density K _u ^FL = 3 × 10 ⁷ erg / c.
c, Curie temperature was estimated to be T _c ^FL = 500K.

FIG. 5 schematically shows a hysteresis loop when the functional layer 12 and the recording layer 11 are laminated.

As shown in FIG. 5, when the absolute value of the magnetic field strength is reduced from the saturation state on the minus side, H ₂ and H ₁
Twice, a sudden change in magnetization appeared. This is the functional layer 12
Means that the recording layer 11 exerts antiferromagnetic exchange coupling interaction with each other.

When the absolute value of the magnetic field strength is reduced from the minus side, first, the functional layer 12 is inverted in H ₂ ,
The spin directions of the recording layer 11 and the functional layer 12 become antiparallel. Since this state is energetically stable, it can be maintained even under a zero magnetic field.

Next, when the magnetic field strength increases toward the plus side, the magnetization of the recording layer 11 is forcibly reversed by the force of the external magnetic field. This is the change in H ₁ .

When this hysteresis loop measurement was carried out while changing the temperature and the temperature change of H ₁ was examined, it was found that it had characteristics such as H _c ^total shown schematically in FIG. This characteristic is brought about by the antiferromagnetic exchange coupling interaction between the functional layer 12 and the recording layer 11.

The dynamic characteristics of the above magnetic recording medium were evaluated by a HDD recording / reproducing evaluation device. Rotation speed is 4500 rp
m, the recording gap was 200 nm, and the reproducing head using the GMR element had a gap of 110 nm. The magnetic spacing was estimated to be 30 nm from the flying height and the thickness of the lubricant. A laser with a wavelength of 633 nm was used for local heating.
The laser was applied to the interface between the functional layer 12 and the recording layer 11 from the back surface of the substrate through the external low flying lens. The external low-flying lens and the substrate were designed to be SIL lenses, and the focal point was set at the interface between the functional layer 12 and the recording layer 11. The diameter of the laser spot is about 500 nm in FWHM. By driving the head with a precise piezo element, the irradiation position of light and the gap position of the recording head were matched.

First, magnetic recording was tried without laser irradiation. It was found that the reproduced signal had almost no noise, and sufficient recording could not be performed. This means that the recording layer 11
This is a natural result in consideration of the coercive force and the recording ability of the recording head.

Next, recording was performed while irradiating the laser. By another experiment and simulation, the relationship between the laser irradiation power and the temperature rise of the magnetic recording medium is grasped in advance, and the irradiation laser power is changed to determine the relationship between the recording temperature Tw and the CN ratio (CNR) of the reproduction signal. Examined. As a result of performing the single frequency recording of 400 kfci, the reproduction signal can be obtained in the region of the recording temperature Tw = 350 K or more, and the recording temperature Tw = 450 K to 550 K
The maximum signal intensity is around, and the recording temperature Tw = 800
The signal disappeared again around K.

The medium temperature dependence of the reproduction signal intensity as described above is appropriate in view of the operation of the above-mentioned heat-assisted magnetic recording system.

Next, after forming the functional layer 12, instead of performing RF sputter etching, a treatment of exposing it to an atmosphere of 1 Pa of Ar and O ₂ for 1 minute is performed, and then the recording layer 11 is formed by the same method as described above. A sample having the protective layer 14 formed thereon was prepared.

As a result of cross-sectional TEM observation, it was found that a CoO layer having a thickness of 1 nm was formed between the functional layer 12 and the recording layer 11.

When the hysteresis curve of this sample was measured, the same one as shown in FIG. 5 was obtained. Based on this result, an SiO ₂ layer having a thickness of 0.8 nm and a Ti layer having a thickness of 1 nm are provided as an intermediate layer between the functional layer 12 and the recording layer 11.
A sample was made in which a layer, a 3 nm Ti layer and a 5 nm thick TiPt layer were inserted.

In any case, the same characteristics as in FIG. 6 are obtained.
It was found that antiferromagnetic coupling was obtained. Inside
When a Ti layer with a thickness of 1 nm is inserted as an intermediate layer, H
₁And H _TwoAnd the exchange coupling energy
It was estimated that Gee was the largest. Middle class
The exchange coupling cannot be obtained if the thickness exceeds 5 nm
It was.

Next, another example of the first embodiment will be described.

First, on the glass substrate 13 of 2.5 inches
A NiAl seed layer (not shown) with a thickness of 5 nm and under V
A formation (not shown) is formed by a 10 nm-thickness sputtering method.
It Then add (Co₁₆Pt₂₄) Cr₁-O machine
The thickness of the functional layer 12 is 10 nm, and the thickness of the Ru intermediate layer (not shown) is thick.
0.8 nm, (Fe₆₃Pt₄₁) Cu₁₂-SiO
_TwoThe recording layer 11 has a thickness of 12 nm, and the C protective layer 14 has a thickness of 3 n.
m Sequentially stack by sputtering method, then apply lubricant
It was

Next, when the fine structure of the recording layer 11 of the magnetic recording medium thus formed was examined by using a TEM, columnar magnetic crystal grains (diameter about 5 nm) mainly made of FePt were formed from amorphous SiO _2. The structure was divided by a non-magnetic material. Cu was distributed almost uniformly in the film.

The magnetic characteristics of the recording layer 11 alone have a major axis of easy magnetization in the in-plane direction, and the magnetic anisotropy energy density K _u ^RL is 8 × 10 ^{7 according to} VSM measurement and magnetic torque measurement.
It was estimated to be erg / cc. The Curie temperature T _c ^RL of the recording layer 11 was estimated to be about 700K.

The magnetic properties of the functional layer 12 were estimated to be magnetic anisotropy energy density K _u ^FL = 1 × 10 ⁷ erg / cc and Curie temperature T _c ^FL = 450K.

The hysteresis loop in the state where the functional layer 12 and the recording layer 11 are laminated is as schematically shown in FIG. 5, and antiferromagnetic coupling is obtained.

This was subjected to the same magnetic recording experiment as above. As a result, the maximum reproduction signal strength is the recording temperature Tw = 4.
Almost similar results were obtained except for the points obtained at 30K to 560K. The recording layer 12 has a crystal grain size of the magnetic substance of 5 nm.
Since it is small, it was confirmed that there is a reproduced signal even at a very high frequency of 1200 kfci. This means that this medium is capable of ultra high density magnetic recording.

Similar samples were prepared by changing the material of the intermediate layer and its thickness. The intermediate layer materials tried were Ru, Re, R
h, Ir, Tc, Au, Ag, Cu, Si, Fe, N
i, Pt, Pd, Cr, Mn, and Al. In all of these, it was confirmed that the film thickness showing antiferromagnetic coupling was in the film thickness region of 5 nm or less.

In any case, the oxide layer, Si
A hysteresis loop indicating a larger exchange coupling energy than that of the O ₂ and Ti alloy layers was obtained. Especially R
Detailed examination of u, Re, Rh, and Ir revealed that
Exchange coupling energy areal density of 1 erg / cm ^{2 to 5} er
It was found to be estimated to be g / cm ² .

Similarly, it has been found that antiferromagnetic exchange coupling also occurs when the semiconductor and the material obtained by doping the semiconductor with a magnetic material are used as the intermediate layer. Here, we tried semiconductors such as Si, Ge, Sn, Te, AlP, GaN, and Ga.
P, GaAs, InSb, ZnO, ZnS, ZnTe
The magnetic substance is Co, Fe, Ni, Mn, or Cr.

The reason why the antiferromagnetic coupling is induced is not clear, but it is presumed that it is probably due to the superexchange interaction between the minority carriers in the semiconductor and the doped magnetic material. Therefore, the base material to be doped may be any semiconductor as long as it can generate a small number of carriers, and the material of the magnetic material is not limited to the above.

Next, another example according to the first embodiment will be described.

First, on a 2.5 inch glass substrate 13, an underlayer (not shown) made of FeTaC soft magnetic having a thickness of 30 nm, a Ti blocking layer (not shown) having a thickness of 5 nm, and P were formed.
t Underlayer (not shown) has a thickness of 10 nm, [Co layer (thickness 0.23 nm) / Pt layer (thickness 0.87 nm)] ₁₀ Functional layer 12, Rh intermediate layer (not shown) has a thickness 0.8 nm,
[Co layer (thickness 0.35 nm) / Pt layer (thickness 0.43
₆ ) The recording layer 11 and the C protective layer 14 were sequentially laminated with a thickness of 3 nm by a sputtering method, and then a lubricant was applied.

The functional layer 12 has a laminated structure of a Co layer having a thickness of 0.23 nm and a Pt layer having a thickness of 0.87 nm.
It is a layered product. The recording layer 11 has a thickness of 0.
The laminated structure is composed of a Co layer having a thickness of 35 nm and a Pt layer having a thickness of 0.43 nm and is laminated six times.

The fine structure of the recording layer 11 of the magnetic recording medium thus formed was examined by using a TEM. As a result, columnar magnetic crystal grains (diameter about 7 nm) mainly composed of a multilayer film of Co and Pt were found. A microstructure was observed in which the was physically separated. The intergranular substance could not be identified, but it is assumed from the constituent materials that it is amorphous Co—O.

The magnetic characteristics of the recording layer 11 and the functional layer 12 alone have a main easy axis in the perpendicular direction,
From the measurement and the magnetic torque measurement, the magnetic anisotropy energy density Ku was estimated to be 1 × 10 ⁷ erg / cc. The Curie temperature Tc was estimated to be about 900K for the recording layer 11 and about 520K for the functional layer 12.

The hysteresis loop in the state where the functional layer 12 and the recording layer 11 were laminated was as shown schematically in FIG. 5, and antiferromagnetic coupling was obtained.

This was subjected to the same magnetic recording experiment as above. As a result, the maximum reproduction signal strength is the recording temperature Tw = 4.
Almost the same result was obtained except that it was obtained in a wide range of 00K to 600K. Since this magnetic recording medium has a small difference in magnetic anisotropy energy density Ku between the recording layer 11 and the functional layer 12, it is conceivable that the thermal fluctuation acceleration phenomenon in the heating portion is suppressed, resulting in a wide temperature margin. It

Next, a sample was prepared in which the intermediate layer of this magnetic recording medium was amorphous ZnSe. Antiferromagnetic exchange coupling was obtained.

FIG. 6 shows the temperature dependence of the reversal magnetic field H _c ^total of the magnetic recording medium thus formed.

As shown in FIG. 6, the reversal magnetic field H _c
^total is from room temperature Ta to Curie temperature T of the functional layer 12.
It sharply decreases to a curved line up to _c ^FL .

[0155] This is different from the example shown in FIG. 3 that the temperature dependency of the exchange coupling energy decreases towards the Curie temperature T _c ^{F L} of the functional layer 11 approximately linear, functional layer 11
This is because the Curie temperature T _c ^{FL is} substantially constant up to the Curie temperature T _c ^FL, which is an effect obtained by using the semiconductor as the intermediate layer.

It has been confirmed that the same effect occurs when the semiconductor used as the intermediate layer is Si, Te, Ge, ZnO or ZnTe. In addition, Co
It was found that the doping energy of Al tends to increase the exchange coupling energy.

Of these, the magnetic recording medium using the ZnSe layer as the intermediate layer was subjected to the same magnetic recording experiment as described above. As a result, it was found that the cross-erase hardly occurs even when the laser is irradiated at a level where the temperature margin spreads to the high temperature side by 50 K and the Curie temperature of the recording layer 11 becomes T _c ^RL .

Next, a magnetic recording medium having the same structure as described above was produced. However, the functional layer 12 is a [Co layer (thickness xn
m) / Pt layer (thickness 0.9 nm)] _6, and [Co layer (thickness 0.28 nm) / Pt layer (thickness 0.43 nm)] ₁₀
For the recording layer 11, the success or failure of the thermally assisted magnetic recording at various x values (corresponding to the difference in the magnetic anisotropy energy density K _u ^{FL of the} functional layer 12) was examined.

The fine structure of the recording layer 11 of this magnetic recording medium was the same as above. In addition, the recording layer 11 and the functional layer 12
Only samples in which and had antiferromagnetic coupling were selected and subjected to a recording / reproducing test. The medium heating temperature Tw was set to be near the Curie temperature T _c ^FL of the functional layer 12.

FIG. 7 shows the result of this recording / reproducing test.

FIG. 7 shows the carrier-noise ratio (CNR) when a single frequency signal recorded at 600 kfci is reproduced.
Is. The CNR is only about 50 dBm at maximum, but it is considered that this is because the relationship between the recording / reproducing system, particularly the heating timing and the recording magnetic field application time, is not optimized. However, even at this level, the suitability of heat-assisted magnetic recording can be sufficiently determined.

As is clear from FIG. 7, K _u ^FL / K _u
^A sufficiently large signal was obtained when ^RL was 0.1 or more. For magnetic anisotropic energy density K _u ^FL is too small magnetic recording medium overall magnetic anisotropy energy density Ku this reason the property was obtained functional layer 11 is decreased, lowering the resistance to thermal fluctuation However, it is considered that fatal thermal fluctuation deterioration occurs even when heated to about the recording temperature. Of course, if the recording temperature is set lower than Tw, thermal fluctuation deterioration can be suppressed. Therefore, even if K _u ^FL / K _u ^RL is less than 0.1, heat assisted recording is possible, and even in this system, it is actually 30 dBm.
It was confirmed that a CNR exceeding 10 was obtained.

Next, a magnetic recording medium having the same structure as described above was produced. However, the functional layer 12 is a [Co layer (thickness xn
m) / Pt layer (thickness 0.9 nm)] ₆ , the recording layer 11 is [C
o layer (thickness 0.28 nm) / Pt layer (thickness ynm)]
X and y were changed in ₁₀ (each of the functional layers 12
Of the magnetic anisotropy energy density K _u ^FL and the Curie temperature T _c ^RL of the recording layer 11) were prepared. The fine structure of the recording layer 11 is the same as above, and only the sample in which the recording layer 11 and the functional layer 12 are antiferromagnetically coupled was selected and subjected to the recording / reproducing test.

Thermally assisted magnetic recording similar to that described above was performed on the magnetic recording medium thus prepared, while changing the irradiation laser power. The medium temperature for each power was estimated by heat conduction analysis simulation.

The results are shown in FIG. The horizontal axis represents the medium heating temperature, and the vertical axis represents the CNR.

As shown in FIG. 8, when the horizontal axis was plotted with temperature, no correlation was found, but when the value was normalized by the Curie temperature T _c ^RL of the recording layer 11, a strong correlation was found. From this result, it was found that a sufficient reproduced signal can be obtained in the recording temperature region where Tw / T _c ^RL is smaller than 0.75. There are variations in the signal strength in this area, but corresponds to the recording power is not always optimum, the signal strength of the Tw / T _c ^{R L} is greater than 0.75 area therewith a clearly lower temperature region This is a small value.

Magnetic anisotropy energy density of the recording layer 11 alone
Degree K_u ^RLIs its Curie temperature T _c ^RLLTowards
Since it decreases linearly, Tw / T_c ^RLIs from 0.75
The larger area is the magnetic anisotropy energy density K_u ^RLIs a room
It is an area where the temperature is less than 1/4 of the value.

The reason why the signal intensity becomes extremely small in this region is considered to be due to the acceleration of thermal fluctuation due to the decrease in the magnetic anisotropy energy density K _u ^RL of the recording layer 11 alone, as described above. Be done.

Regarding the results obtained in FIG. 8, the recording temperature at which the largest CNR was obtained was selected for each sample, and it was plotted against T _c ^FL / T _c ^RL . The result is shown in FIG.

As shown in FIG. 9, it was found that a sufficient reproduced signal can be obtained when T _c ^FL / T _c ^RL is smaller than 0.75. As described above, assuming that there is no thermal fluctuation deterioration of the recording layer 11, the maximum CNR is obtained when the recording temperature is near the Curie temperature T _c ^FL of the functional layer 12.

Magnetic anisotropy energy density of the recording layer 11 alone
Degree K_u ^RLIs its Curie temperature T _c ^RLToward
Since it decreases to near, T_c ^FL/ T_c ^RLIs 0.75
The larger region is the Curie temperature T of the functional layer 12._c ^FLTo
Magnetic anisotropy energy density K in_u ^RLIs at room temperature
This is the case when it is less than 1/4. This time, big
Curie temperature T of the functional layer 12 where signal strength is expected_c
^FLIn the vicinity of heating, thermal fluctuation deterioration of the recording layer 11 occurs.
As a result, the signal becomes smaller, resulting in
I can only record by heating at lower temperatures.
It seems to be a tame.

(Embodiment 2) Next, Embodiment 2 of the present invention
The magnetic recording apparatus according to the present invention will be described.

This magnetic recording device comprises a non-magnetic substrate, a functional layer formed on the non-magnetic substrate and made of a ferrimagnetic material having a smaller amount of magnetization at room temperature than at room temperature and above the functional layer. A recording layer composed of magnetic particles and a non-magnetic material formed between the magnetic particles, which are laminated so as to exert an antiferromagnetic exchange coupling interaction with the functional layer at room temperature, and heating for heating the functional layer and the recording layer. And magnetic recording means for recording signal magnetization by applying a magnetic field to the recording layer.

The magnetic recording apparatus according to the first embodiment shown in FIG. 2 is different in that the functional layer 12 is a ferrimagnetic material and that the functional layer 12 and the recording layer 11 are ferromagnetically exchange-coupled. The configuration is the same.

The feature of the present invention is that the magnetization of the functional layer 12 as viewed from the recording layer 11 increases with temperature.
In general, the magnetization of the magnetic material decreases with temperature, so in order to obtain this effect, the antiferromagnetic coupling is used in the first embodiment.

On the other hand, in the second embodiment, the functional layer 12
It is characterized in that the functional layer 12 and the recording layer 11 are coupled by ferromagnetic coupling by using a ferrimagnetic material which has a characteristic that the magnetization increases with temperature.

Ferrimagnetism is generally found in a system in which two spins of different effective magnitudes are antiferromagnetically coupled. The state is schematically shown in FIG.

As shown in FIG. 10, in the ferrimagnetic material, the spins U and L are coupled in opposite directions, and the Curie temperatures are different from each other, so that the temperature change of the magnetization is not uniform. Particularly high saturation magnetization Ms and low Curie temperature Tc
In the case of the combination of the spin L having R and the saturation U having a low saturation magnetization Ms and a high Curie temperature Tc, the magnetization has a characteristic of increasing with temperature.

Therefore, by using the ferrimagnetic material having the characteristic of increasing the magnetization when the temperature rises as described above as the functional layer 12 and using the recording layer 11 which is ferromagnetically exchange-coupled with the functional layer 12, the characteristics similar to those shown in FIG. 3 are obtained. Show the effect.

FIG. 11 shows the saturation magnetization M _s ^FL of the functional layer 12 and the magnetic anisotropy energy density K of the recording layer 11 at this time.
_u ^RL , the change in temperature of the ^total reversal magnetic field H _c ^total is shown.

With the increase of the saturation magnetization M _s ^FL of the functional layer 12, the reversal magnetic field H _c ^total decreases sharply with respect to the temperature that the recording layer 11 originally has. This makes it possible to obtain a magnetic recording medium in which thermal fluctuation acceleration deterioration is small as in the first embodiment and the influence of the demagnetizing field is small.

The only essential condition for obtaining the action shown in FIG. 11 is that the magnetization amount (net moment) of the functional layer 12 is larger at room temperature than at room temperature. The magnitude relationship between the Curie temperature of the functional layer 12 and the Curie temperature or the recording temperature of the recording layer 11 is arbitrary.

In the magnetic recording device according to the present invention, the functional layer 12 is made of a rare earth metal and a transition metal alloy. Those exhibiting ferrimagnetism are, for example, TbFe, TbFeCo,
TbCo, GdTbFeCo, GdDyFeCo, Nd
There are amorphous rare earth and transition metal alloy thin films such as FeCo and NdTbFeCo, and ordered alloys such as CrPt _3. Especially, amorphous rare earth (RE) and transition metal (TM) alloy thin films are practically used as magneto-optical (MO) recording media. It is preferable to set the rare earth-rich composition, the compensation composition, or the transition metal-rich composition in the vicinity of the compensation composition because the characteristic that the magnetization increases with temperature as shown in FIG. 10 is easily obtained.

Further, in the magnetic recording device according to the present invention, the first functional layer in which the functional layer 12 is a magnetic substance and the second functional layer in which the functional layer 12 is a magnetic substance are laminated so as to be antiferromagnetic exchange-coupled. The Curie temperature is different between the first functional layer and the second functional layer, and the laminated structure is repeated one or more times. By doing so, a material that exhibits artificial ferrimagnetism can be obtained.

A first functional layer that is a magnetic material (typically C
o, Ni, Fe or alloys thereof) and a second functional layer which is another magnetic layer are laminated in this order, and the multilayer structure is repeated one or more times. When the antiferromagnetic exchange coupling interaction works between the one functional layer and the second functional layer, and the magnetic properties of the first functional layer and the second functional layer have a relationship as shown in FIG. It can be used as the same ferrimagnetic functional layer. To make the antiferromagnetic exchange coupling interaction work,
For example, a nonmagnetic layer having a thickness of 5 nm or less (eg Ru, Re, R
h, Ir, Tc, Au, Ag, Cu, Mn, Si, Cr
Alternatively, these alloys or oxides) may be inserted between the first functional layer and the second functional layer.

Also, what is called an antiferromagnetic material,
Ferrimagnetism may be exhibited depending on conditions such as temperature conditions and crystal orientation planes, and in such a case, this can also be used as the functional layer.

As the material exhibiting antiferromagnetism, there is a thin film of an antiferromagnetic material having a Neel temperature higher than room temperature. For example, an alloy of Fe, Cr, and Co, specifically Mn
Ni, MnPd, MnPt, CrPd, CuMn, Au
Mn, AuCr, CrMn, CrRe, CrRu, Fe
Mn, CoMn, FeNiMn, CoMnFe, IrM
n, etc., and an ordered alloy, specifically AuM
n, ZnMn, FeRh, FeRhIr, Au ₂ Mn,
Au ₅ Mn ₁₂ , Au ₄ Cr, NiMn, PdMn, P
There are tMn, PtCr, PtMn ₃ , RhMn _{3, and the} like, and in addition to these, Mn ₃ PtN, CrMnPt, PdPt.
Mn, NiO, CoO, etc. are known.

The magnetic recording device according to the present invention is characterized in that the laminated structure of the functional layer 12 and the recording layer 11 is repeatedly laminated one or more times. The pair of the functional layer 12 and the recording layer 11 described so far does not have to be a pair. For example, a structure of substrate / base / functional layer / recording layer / functional layer / recording layer may be used.

In such a case, the interface per recording layer or functional layer is doubled, which is an advantage that the exchange coupling energy is substantially doubled. The advantages brought about by the increased exchange coupling energy have already been described.

In this case, since the total film thickness tends to be large, it is preferable that the functional layer or recording layer forming the laminated structure is thin.

Next, the magnetic recording medium according to the second embodiment will be specifically created.

First, a SiN underlayer (not shown) having a thickness of 50 nm and Tb was formed on a glass substrate 13 having a thickness of 2.5 inches.
₂₂ (Fe ₈₅ Co ₁₅ ) functional layer 12 having a thickness of 15 nm,
[Co layer (thickness 0.28 nm) / Pt layer (thickness 0.43 nm
₁₀ nm recording layer 11 and C protective layer 14 having a thickness of 3 nm were sequentially stacked by a sputtering method, and then a lubricant was applied. At this time, the functional layer 12 and the recording layer 11 were continuously deposited without breaking the vacuum. Further, the recording layer 11 is formed by stacking 10 layers of a layered structure including a Co layer having a thickness of 0.28 nm and a Pt layer having a thickness of 0.43 nm.

When the fine structure of the recording layer 11 of the magnetic recording medium thus formed was examined by using TEM,
A fine structure in which columnar magnetic crystal grains (diameter of about 7 nm) mainly composed of a multilayer film of Co and Pt were physically separated was observed. The intergranular substance could not be identified, but it is assumed from the constituent materials that it is amorphous Co—O.

The magnetic characteristics of the recording layer 11 and the functional layer 12 alone have a main easy axis in the perpendicular direction, and the magnetic anisotropy energy density of the recording layer 11 is K _u ^RL = 1 by VSM measurement and magnetic torque measurement. It was estimated to be × 10 ⁷ erg / cc. Since the functional layer 12 is close to the compensating composition, it is difficult to evaluate the magnetic anisotropy energy density.
It was estimated that _u ^FL = 6 × 10 ⁶ erg / cc.
The Curie temperature of the recording layer 11 is T _c ^RL = about 900.
K, the functional layer 12 was estimated to be T _c ^FL = about 600K.

FIG. 12 shows a hysteresis loop when the functional layer 12 and the recording layer 11 are laminated.

As shown in FIG. 12, this hysteresis loop was shifted to the positive magnetic field side by one step. This is because the functional layer 12 and the recording layer 11 are ferromagnetically exchange-coupled, and the functional layer 11 does not undergo magnetization reversal due to the compensation composition.

The spin directions of the functional layer 12 and the recording layer 11 are schematically shown in FIG. The upper part is the recording layer 11, and the lower part is the functional layer 12.

The spin direction of the functional layer 12 is set under the conditions at the time of film formation or other reasons. Since it is a compensating composition, the magnetization does not reverse (the direction does not change) in the measurement magnetic field range (for example, 20 kOe). When the magnetic field is negatively large, the spins of the functional layer 12 and the recording layer 11 follow the external magnetic field and face downward. As the magnetic field strength in the plus direction increases, the spin of the recording layer 11 increases in upward force.
The ferromagnetic exchange coupling force from the functional layer 12 receives a large force in the downward direction, so that it does not easily reverse. Still, the magnetization reversal occurs under the large magnetic field H ₁ .

The state is shown in the upper right portion of FIG.
If you reduce the external magnetic field from here and move it to the negative side,
The external field that directs the spin of the recording layer 11 disappears, but the inversion does not occur even under a zero magnetic field due to the anisotropic energy of the recording layer 11. However, since it is always receiving a downward force due to the ferromagnetic exchange coupling force, reversal occurs in the magnetic field H ₂ smaller than H ₁ . Therefore, it is understood that this medium is ferromagnetically exchange-coupled by obtaining such hysteresis.

When this hysteresis loop measurement was carried out while changing the temperature and the temperature change of H ₁ was examined, it was found that it had characteristics like the reversal magnetic field H _c ^total shown schematically in FIG.

The saturation magnetization of the functional layer 12 is also as schematically shown in FIG. These characteristics are related to the functional layer 1
2 and the recording layer 11 are ferromagnetically exchange-coupled, and the magnetization of the functional layer 12 increases from room temperature toward a high temperature region.

The dynamic characteristics of the above magnetic recording medium were evaluated by an HDD recording / reproducing evaluation device. Rotation speed is 4500 rp
m, the recording gap was 200 nm, and the reproducing head using the GMR element had a gap of 110 nm. The magnetic spacing was estimated to be 30 nm from the flying height and the thickness of the lubricant. A laser with a wavelength of 633 nm was used for local heating.
The laser was applied to the functional layer / switching layer / recording layer portion from the back surface of the substrate through the external low flying lens. The external low-flying lens and the substrate were both designed to be SIL lenses so that the focal point would be located at the functional layer / switching layer / recording layer portion. The diameter of the laser spot is about 500 nm in FWHM. By driving the head with a precise piezo element, the irradiation position of light and the gap position of the recording head were matched.

First, magnetic recording was tried without laser irradiation. It was found that the reproduced signal contained almost no noise, and sufficient recording could not be performed. This means that the recording layer 11
This is a natural result in consideration of the coercive force and the recording capability of the recording head 1.

Next, recording was performed while irradiating the laser. As a result of recording a single frequency of 400 kfci, the maximum C at a recording temperature Tw close to T _peak.
HR was obtained.

Further, the same Tb composition was changed and the same magnetic characteristic evaluation and recording / reproducing experiment were conducted. FeCo
It was confirmed that in the so-called RE-rich composition in which the Tb composition is larger than that in (1), the change in magnetic characteristics with temperature is the same as in FIG. 11, and that heat-assisted magnetic recording can be performed with all the investigated compositions.

On the other hand, it was found that there are two cases as shown in FIGS. 13 and 14 in the so-called TM-rich composition having a small Tb composition.

FIG. 13 is TM rich but close to the compensation composition, and FIG. 14 is far from the compensation composition. As a result of the recording / reproducing test, only the prepared sample showed the characteristics as shown in FIG. 13 and the thermally assisted magnetic recording was possible. This indicates that the thermally assisted magnetic recording is possible only when the temperature change of the magnetization increases from the room temperature toward the high temperature region.

The reason is that as the temperature rises, the functional layer 12
This is because the apparent magnetization of the exchange-coupled functional layer 12 and the recording layer 11 also increases, and as a result, the coercive force decreases and recording becomes possible. When the functional layer 12 whose magnetization does not increase is used, the magnetization of the two-layer film of the functional layer 12 and the recording layer 11 also decreases with temperature, so that the coercive force cannot be reduced more rapidly than in the case of a single recording layer.

A sample in which the functional layer 12 was made of CrPt ₃ was also prepared. It was found that the temperature dependence of the magnetic characteristics is the same as in FIG. 11, and that heat-assisted magnetic recording is also possible.
From this, the thermally assisted magnetic recording according to the present invention is possible because the functional layer 12 is ferromagnetically exchange-coupled and its saturation magnetization increases with temperature. It turns out that it doesn't get along essentially.

A magnetic recording medium similar to the above was prepared. However, the functional layer 12 is made of Co ₉₀ Cr ₁₀ as the first functional layer.
Layer (thickness 0.6 nm), Ru layer (thickness 0.75 nm), Co layer (thickness 0.25 nm) and Ru as the second functional layer
A layer (thickness 0.75 nm) was used as a laminated structure, which was laminated four times.

It was confirmed from the hysteresis loop that the functional layer 12 has a magnetic structure in which the CoCr magnetic layer and the Co magnetic layer are antiferromagnetically coupled.

The Curie temperature of the CoCr magnetic layer alone is about 500 K, and the Curie temperature of the Co magnetic layer alone is 1.
It is 200K. Therefore, the temperature dependence of the magnetic properties of the functional layer 12 alone is a CoCr dominant at room temperature but becomes a dominant Co at high temperature due to the difference in Curie temperature, and the ferrimagnetism as shown in FIG. Show.
Therefore, it can be used for a heat-assisted magnetic recording medium exactly as described above.

Several samples having different thicknesses of the first functional layer and the second functional layer were prepared and the same recording / reproducing experiment as above was conducted. As a result, it was found that the thermally assisted magnetic recording can be performed only on the sample having the saturation magnetization value at room temperature of the first functional layer having a small Curie temperature that is larger than that of the second functional layer. The reason for this is that the success or failure of the thermally assisted magnetic recording is the functional layer 1.
It is essentially due to the magnetization of 2 increasing with temperature.

[0214]

As described above, according to the present invention,
It is possible to perform magnetic recording without causing remagnetization reversal due to thermal fluctuation acceleration.

[Brief description of drawings]

FIG. 1 is a perspective view of a magnetic recording device according to the present invention.

FIG. 2 is a sectional view of a magnetic recording device according to the present invention.

FIG. 3 is a diagram schematically showing changes in magnetic anisotropy and reversal magnetic field of a recording layer and a functional layer of a magnetic recording device according to Embodiment 1 of the present invention with respect to a medium temperature.

FIG. 4 is a diagram schematically showing changes in magnetization of a recording layer and a functional layer of a magnetic recording device according to Embodiment 1 of the present invention with respect to heat application, where (a) is before heat application, (b) and (c). () Is during heat application, (d) is after heat application.

FIG. 5 is a diagram schematically showing a hysteresis loop of the magnetic recording device according to the first embodiment of the invention.

FIG. 6 is a diagram schematically showing changes in magnetic anisotropy and reversal magnetic field of a recording layer and a functional layer with respect to a medium temperature in another example of the magnetic recording device according to the first embodiment of the present invention.

FIG. 7 is a diagram showing changes in CNR with respect to K _u ^FL / K _u ^RL in another example of the magnetic recording device according to the first embodiment of the present invention.

FIG. 8 is a diagram showing changes in CNR with respect to Tw / T _c ^RL in another example of the magnetic recording device according to the first embodiment of the present invention.

FIG. 9 is a diagram showing changes in CNR with respect to T _c ^FL / T _c ^RL in another example of the magnetic recording apparatus according to the first embodiment of the present invention.

FIG. 10 is a diagram showing a relationship between magnetization and temperature of a functional layer of a magnetic recording device according to a second embodiment of the present invention.

FIG. 11 is a diagram schematically showing changes in magnetic anisotropy and reversal magnetic field of the recording layer and the functional layer of the magnetic recording apparatus according to the second embodiment of the present invention with respect to the medium temperature.

FIG. 12 is a diagram schematically showing a hysteresis loop of the magnetic recording medium according to the second embodiment of the present invention.

FIG. 13 is a diagram schematically showing changes in magnetic anisotropy, switching magnetic field, and magnetization of a recording layer and a functional layer with respect to a medium temperature in another example of the magnetic recording device according to the second embodiment of the present invention.

FIG. 14 is a diagram schematically showing changes in magnetic anisotropy, switching magnetic field and magnetization of a recording layer and a functional layer with respect to a medium temperature in a comparative example of the magnetic recording device according to the second embodiment of the present invention.

[Explanation of symbols]

11 ... Recording layer 12 ... Functional layer 13 ... Substrate 14 ... Protective layer 1 ... Recording head and heating source 31 ... Magnetic particles 32 ... Non-magnetic intergranular substance 33 ... Transition formation position 34 ... Heating area

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshihiko Nagase             1st Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa             Inside the Toshiba Research and Development Center (72) Inventor Tomoyuki Maeda             1st Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa             Inside the Toshiba Research and Development Center (72) Inventor Junichi Akiyama             1st Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa             Inside the Toshiba Research and Development Center F-term (reference) 5D006 BB07 BB08 DA00 DA03                 5D075 AA10 CD06 CE20                 5D091 CC30

Claims (11)

[Claims] 1. A non-magnetic substrate, a functional layer formed on the non-magnetic substrate and comprising a magnetic material having a Curie temperature T _c ^FL and a magnetic anisotropy energy density K _u ^FL , and the above-mentioned functional layer having the above-mentioned functional layer. the Curie temperature T _c ^FL and recording temperature higher Curie temperature T _c than either of Tw stacked to exert anti-ferromagnetic exchange coupling interaction with the functional layer
A recording layer made of a nonmagnetic material formed between the magnetic particles and the magnetic particles having a ^RL and 5 × 10 6 ^erg / cc or more magnetic anisotropy energy density K _u ^{R L,} the functional layer and the recording A magnetic recording apparatus comprising: heating means for heating a layer to the recording temperature Tw; and magnetic recording means for recording signal magnetization by applying a magnetic field to the recording layer. 2. The magnetic anisotropy energy density K_u ^FLBut
The magnetic anisotropy energy density K_u ^RLBe less than
The magnetic recording device according to claim 1, wherein 3. The magnetic anisotropy energy density K_u ^FL>
The magnetic anisotropy energy density K_u ^RL× 0.1
The magnetic recording device according to claim 2, wherein 4. The magnetic anisotropic energy density K _u ^RL at the recording temperature Tw is larger than ¼ of the anisotropic energy density K _u ^RL at room temperature. 3. The magnetic recording device according to any one of 3 above. 5. A to claim 1, wherein the Curie temperature _T ^c the magnetic anisotropic energy density _K in ^{FL u RL} is equal to or greater than 1/4 of the magnetic anisotropy energy density _K ^{u RL} at room temperature The magnetic recording device according to claim 4. 6. A thickness of 5 n is provided between the recording layer and the functional layer.
The magnetic recording device according to claim 1, further comprising a non-magnetic intermediate layer having a thickness of m or less. 7. The non-magnetic intermediate layer is at least Ru, R
e, Rh, Ir, Tc, Au, Ag, Cu, Si, F
7. The magnetic recording device according to claim 6, wherein the magnetic recording device is made of a material selected from e, Ni, Pt, Pd, Cr, Mn, Al, a semiconductor, and a semiconductor in which a magnetic material is doped. 8. A non-magnetic substrate, a functional layer formed on the non-magnetic substrate and made of a ferrimagnetic material having a magnetization amount at room temperature larger than that at a recording temperature Tw, and the functional layer on the functional layer. A recording layer composed of magnetic particles laminated so as to exert a ferromagnetic exchange coupling interaction and a non-magnetic material formed between the magnetic particles, and the functional layer and the recording layer are heated to the recording temperature Tw. A magnetic recording device comprising: heating means; and magnetic recording means for recording signal magnetization by applying a magnetic field to the recording layer. 9. The magnetic recording apparatus according to claim 8, wherein the functional layer is made of a rare earth metal and a transition metal alloy. 10. A laminated structure in which the functional layer includes a first magnetic layer and a second magnetic layer that is antiferromagnetically exchange-coupled with the first magnetic layer, is laminated a plurality of times to form the first magnetic layer. 9. The magnetic recording device according to claim 8, wherein the body layer and the second magnetic layer have different Curie temperatures. 11. The magnetic recording device according to claim 8, wherein a laminated structure including the functional layer and the recording layer is laminated a plurality of times.