JPH0668465A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the process for production of the magnetic recording medium which can deal with a trend toward higher densities and having high coercive force. CONSTITUTION:This process for production of the magnetic recording medium includes a stage for cooling a laminate formed by laminating a metallic recording layer contg. a ferromagnetic material having the coefft. of thermal expansion larger than the coefft. of thermal expansion of a substrate on this substrate directly or via a ground surface layer from a temp. Ta1 of 300 to 450 deg.C down to a temp. Ta2 of <=150 deg.C or from a temp. Tb1 of 450 to 700 deg.C down to a temp. Tb2 lower by >=300 deg.C from the above-mentioned temp. Tb1 at >=10 deg.C/min average cooling rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium used for a hard disk or the like.

[0002]

2. Description of the Related Art In recent years, the capacity of hard disk devices has increased,
The tendency toward miniaturization and high speed is remarkable, and higher recording density is required for the magnetic recording medium used in this type of device. For a magnetic recording medium, the most important magnetic characteristics for achieving high recording density are high coercive force and residual magnetization.

As a conventional method of manufacturing a magnetic recording medium of this type, Japanese Patent Application Laid-Open No. 62-117143 discloses that a substrate is
What has a step of stacking a recording layer made of a metal and then holding it in a vacuum or an inert gas at 250 to 600 ° C. for about 1 to 30 hours to clarify the crystal grain boundary and develop the crystal. It is disclosed. It should be noted that this publication does not describe the cooling step after the above-mentioned heat treatment, and the magnetic recording medium is usually manufactured by cooling after the heat treatment.

[0004]

However, the coercive force of the magnetic recording medium obtained by the above method is 900 (Oe).
The degree is limited, and the holding power is too low as it can cope with the future high density, and it is desired to introduce a magnetic recording medium having a higher holding power. Therefore, an object of the present invention is to provide a method of manufacturing a magnetic recording medium having a higher coercive force, which can cope with higher density.

[0005]

The first method of manufacturing a magnetic recording medium of the present invention which achieves the above object (hereinafter, this method is referred to as the first method for convenience) is directed to a substrate directly or via an underlayer. Then, from the cooling start temperature T _a1 of 300 ° C. to 450 ° C., a laminated body in which a metal recording layer containing a ferromagnetic material having a thermal expansion coefficient larger than that of the substrate is laminated is
It is characterized by including a step of cooling at a rate of 10 ° C./min or more on average to a temperature T _a2 of 0 ° C. or less.

A second method for manufacturing a magnetic recording medium of the present invention which achieves the above object (hereinafter, this method will be referred to as a second method for convenience).
Method), a laminated body in which a metal recording layer containing a ferromagnetic material having a coefficient of thermal expansion larger than that of the substrate is laminated on the substrate directly or via an underlayer.
From a cooling start temperature T _b1 of 50 ° C. to 700 ° C. to a temperature T _b2 lower than the cooling start temperature by 300 ° C. or more, an average of 10 ° C.
It is characterized by including a step of cooling at a rate of not less than / min.

The present invention will be described in detail below. Method for manufacturing magnetic recording medium of the present invention (first method and second method)
Then, after forming a metal thin film containing a ferromagnetic material directly on the substrate or via an underlayer, the substrate with the ferromagnetic metal thin film is cooled at a predetermined high cooling rate from a predetermined high substrate temperature to near room temperature. Therefore, due to the difference in the thermal expansion coefficient between the substrate and the ferromagnetic metal thin film, a large internal stress, so-called thermal stress, is brought into the ferromagnetic metal thin film, and as a result, the magnetic anisotropy is produced due to the inverse magnetostriction effect peculiar to the ferromagnetic metal. Is brought about. For this reason, this effect is added to the in-plane anisotropy inherent in the medium, so that a large coercive force that cannot be obtained by the conventional metal thin film medium is realized while minimizing the decrease in remanent magnetization.

This action will be described more specifically below. As an example, a case of a laminated body in which a cobalt magnetic layer is formed on an aluminosilicate glass substrate will be described. At this time, the direction of thermal expansion and the magnetic properties are assumed to be isotropic in the plane of the medium.

When a laminated body having a magnetic thin film formed on a substrate is rapidly cooled from a certain heat treatment temperature, the internal stress generated in the magnetic thin film is expressed by the following equation (1). _{P = E (α s -α m} ) (t a -t s) [kg / mm 2] ... (1) where, E: Young's modulus of the magnetic thin film _{^{[kg / mm 2] α s}} : thermal expansion of the substrate coefficient alpha _m: thermal expansion coefficient of the magnetic thin film t _a: heat treatment temperature = cooling start temperature [℃] t _s: for temperature [℃] the laminate after cooling, the Young's modulus E = 21 × 10 cobalt
³ kg / mm ² , α _s = 91 × 10 ⁻⁷ , α _m = 123 ×
When 10 ^-7 is set and when rapidly cooled from t _a = 400 ° C. to t _s = room temperature 25 ° C., P = 25.2 kg / mm ² . At this time, since the sign of P is positive, it is a tensile stress.

Here, when the magnetostriction constant is positive, when the magnetic body is magnetized, the length thereof extends in the magnetization direction. At this time, if a tensile stress is present as an internal stress, the stress is relaxed by the elongation of the length, that is, the energy changes to a smaller stable state, so that the magnetization is magnetically promoted. As a result, the coercive force will increase. If this is generalized, the coercive force Hc increases when the stress and the sign of the magnetostriction constant match, and decreases when they do not match.

The change (ΔHc) in coercive force due to internal stress is expressed by equation (2). ΔHc = 3λσ / Ms [Oe] (2) where λ: magnetostriction constant σ: internal stress [dyne / cm ² ] Ms: saturation magnetization [G] magnetostriction constant of cobalt alloy λ = 50 × 10 ⁻⁶ , saturation Magnetization M
With s = 1400 G, the internal stress P obtained above is 25.2.
Using kg / mm ² , ΔHc = 265 (Oe). Therefore, due to the rapid cooling, the coercive force Hc in this case is 2
It will be increased by 650 (Oe).

Table 1 shows the calculation results of the coercive force change ΔHc when the Co magnetic film and various substrates are combined.

[0013]

[Table 1] It can be seen from Table 1 that the coefficient of thermal expansion of quartz glass is small and therefore the change in coercive force is very large. Further, in the case of the Al substrate, the coefficient of thermal expansion is larger than Co, so that the Co magnetic film becomes a compressive stress and the coercive force is reduced. Thus C
It can be seen that in the case of the o alloy thin film medium, the Al substrate does not provide the effect of improving the coercive force by rapid cooling.

In the above formula, since the film thickness of the recording layer and the cooling rate of the laminated body are not taken into consideration, the change of the coercive force of the magnetic recording medium obtained by actual manufacturing is considered. Although it is not the same as the above calculation result, when at least the coefficient of thermal expansion of the substrate is smaller than that of the recording layer, the holding force tends to increase as shown in the following examples. Further, the operation of the present invention has been described so far in the case where the recording layer is directly laminated on the substrate. However, even when the underlayer made of Cr or the like is formed between the substrate and the recording layer, A similar tendency is exhibited, and the holding power is increased. The reason for this is that the thickness of the substrate is usually several mm or more, whereas the thickness of the recording layer and the underlying layer is only about several thousand angstroms at the most, so that the underlying layer is between the substrate and the recording layer. This is because it is not possible to reduce the difference in the expansion coefficient of.

The method of manufacturing the magnetic recording medium of the present invention will be described in more detail below.

In the present invention, the average cooling rate is the cooling start temperature T _a1 in the first method and the time t at that time.
_a1 , temperature T _a2 at the end of quenching, and time t _a2 at that time, (T _a1 −T _a2 / t _a2 −t _a1 ). In the second method, the average cooling rate is the cooling start temperature T _b1 , the time t _b1 at that time, and the temperature T at the end of the rapid cooling.
_b2 , when represented by time t _b2 at that time, (T _b1 −T _b2 / t
_b2 is the meaning of -t _b1). In the first and second methods, the average cooling rate is set to 10 ° C./minute or more,
This is because if it is less than 10 ° C./min, the internal stress does not become large and the above-mentioned inverse magnetostriction effect becomes difficult to occur, so that the holding force cannot be made large. It is preferably 30 ° C./minute or more. In addition, you may cool at a rate of less than 10 degree-C / min after this rapid cooling. For reference, for example, 400
The average cooling rate in the case of cooling the laminated body at 150 ° C. to 150 ° C. is at most about 5 ° C./min.

The cooling start temperature is T in the first method.
_a1 = 300 to 450 ° C., T _b1 = 450 in the second method
Although the temperature is set to ˜700 ° C., in order to achieve the object of the present invention, the cooling start temperature may be set to either of these ranges. That is, in the present invention, the cooling start temperature may be set to 300 to 700 ° C. The reason why the cooling start temperature is set to 300 to 700 ° C. is that if the temperature is lower than 300 ° C., the internal stress does not increase, the above-described inverse magnetostriction effect hardly occurs, and the coercive force cannot be increased. , On the contrary, 700
This is because if the temperature exceeds ℃, the crystal grows and the grain size becomes too large, and the coercive force of the residual magnetization is remarkably lowered, causing an increase in noise. The cooling start temperature is preferably 34
0 ° C to 660 ° C, that is, in the first method, the preferable range of the cooling start temperature T _a1 is 340 to 450 ° C, and in the second method, the preferable range of the cooling start temperature T _b1 is 45.
It becomes 0-660 degreeC.

In the first method, the temperature T _a2 at the end of quenching is set to 150 ° C. or lower.
This is because at 0 ° C. or lower, even if the cooling rate is reduced, there is almost no influence on the thermal stress and the inverse magnetostriction effect. Therefore, in the first method, the temperature T _a2 at the end of quenching is set to 150.
The temperature shall be below ℃.

On the other hand, in the second method, the temperature T _{b2 at the} end of the rapid cooling is set to be a temperature lower than the cooling start temperature T _b1 by 300 ° C. or more and not limited to 150 ° C. or less. The difference between T _b1 and the quenching end temperature T _b2 is 300 ° C.
This is because, since the above is performed, a sufficiently large internal stress can be obtained and the holding force can be increased. In the second method as well, the temperature T _b2 at the end of quenching is set to 1
A temperature of 50 ° C. or lower is preferable in order to obtain higher holding power.

In the present invention, it is desired that the substrate be able to withstand the above heat treatment and have a smaller coefficient of thermal expansion than the recording layer. Therefore, the substrate is a glass substrate (aluminosilicate glass, soda lime glass, quartz glass, etc.) or a ceramic substrate (Al ₂ O ₃ system, Zr).
O ₂ type, Al ₂ O ₃ —TiC (Altic) and the like) are preferable.

Further, C is provided between the substrate and the recording layer.
An underlayer made of r or the like may be provided, and a protective layer made of carbon, Cr, silicon oxide, silicon nitride or the like may be provided on the recording layer.

The heat treatment step may be performed any time after the recording layer is provided. That is, in the case of providing a protective layer on the magnetic recording medium, heat treatment may be performed after forming the protective layer, or the protective layer may be formed after performing heat treatment.

Further, the method of bringing the laminate to the cooling start temperature is as follows. After the recording layers and the like are laminated at a temperature lower than the cooling temperature (for example, room temperature) to obtain a laminate, the laminate is heated to a high temperature. And a predetermined cooling start temperature, and a method of stacking the recording layers and the like at the cooling start temperature and holding the laminated body at the cooling start temperature until the cooling starts.

In the former method, the time for holding the substrate at a high temperature may be any time that the substrate can be kept within a predetermined cooling start temperature. If this time is too long, crystals grow and the grain size becomes too large, resulting in a decrease in the residual magnetization coercive force. Also, the higher the temperature, the shorter this time should be. For example, the cooling start temperature is 4
If it is 00 ° C., this temperature is usually maintained for about 10 minutes to 10 hours, but it is preferable to shorten this time as the cooling start temperature becomes higher.

[0025]

EXAMPLES Examples of the present invention will now be described in detail, but the present invention is not limited to these examples. The sputtering apparatus used in the examples of the present invention includes a sputtering chamber having a plurality of targets and an annealing chamber for performing annealing. To prevent oxidation of the metal layer on the substrate,
Both chambers are connected by a tube equipped with a valve so that the substrate can be moved between the chambers without being exposed to the atmosphere. Further, both chambers are independently equipped with a vacuum pump and a system for introducing gas such as nitrogen and argon. Further, in the annealing chamber, the pallet holding the substrate is equipped with a cooling water pipe, and the cooling rate can be controlled by adjusting the temperature of the water or the flow rate of the water.

In this example, a sample vibrating magnetometer (Model 880 manufactured by Digital Measurement System Co., Ltd.) was used to measure the magnetic properties (coercive force and residual magnetization).

(Examples 1 to 6) After setting the aluminosilicate glass substrate in the sputtering chamber, the chamber was set at 4 × 10 ^-7.
Evacuated until reaching Torr. Subsequently, Ar gas was introduced. At this time, the Ar gas pressure was 10 mTorr. A Cr non-magnetic material layer as a base layer was laminated on a glass substrate at a rate of 350 angstroms / minute for 3000 angstroms by sputtering, and a CoNiCr ferromagnetic material layer (Co / Ni / Cr = 65) was formed thereon as a recording layer.
/ 25/10) was laminated at a rate of 400 Å / min to 500 Å. In this way, six laminated bodies having a two-layer structure were obtained on the substrate.

These laminated bodies are moved to an annealing chamber,
In order to prevent the recording layer from being oxidized, the degree of vacuum in the chamber is 2 × 10 ^-5 To
After evacuating until reaching rr, the annealing chamber was heated at a heating rate of 5 ° C./min to a predetermined cooling start temperature T _a1 or T _b1 (° C.), respectively, as shown in Table 2. As shown, after holding at that temperature for a predetermined time t (hr), at a predetermined cooling rate v (° C / min), a predetermined cooling end temperature T _a2
Alternatively, it was rapidly cooled to T _b2 (° C.) and then left to cool.

After that, each laminated body was moved to a sputtering chamber, and a carbon protective layer was laminated at 300 angstrom at a rate of 200 angstrom / minute to obtain a magnetic recording medium. The coercive force and residual magnetization of the obtained magnetic recording medium are
As is clear from the description in Table 2, the holding force (Hc) is 12
10-1870 (Oe), remanent magnetization (Mr) is 451-
A large value of 710 emu / cc was obtained, which was excellent. That is, it was found that the magnetic recording media obtained in Examples 1 to 6 could be applied to high density recording.

[0030]

[Table 2] (Examples 7 to 10) The quartz glass substrate was set in the sputtering chamber, and then the chamber was evacuated until it reached 4 × 10 ^-7 Torr. Subsequently, Ar gas was introduced. Ar at this time
The gas pressure was 10 mTorr. A Cr non-magnetic layer is formed on the glass substrate by sputtering as an underlayer.
A 3000 angstrom layer was formed at a rate of angstrom / minute, and a CoNiCr ferromagnetic layer (Co / Ni / Cr = 65/25/10) was formed as a recording layer on this layer at a rate of 400 angstrom / minute. In this way, four laminated bodies having a three-layer structure were obtained on the substrate.

These laminated bodies are moved to an annealing chamber,
In order to prevent the recording layer from being oxidized, the degree of vacuum in the chamber is 2 × 10 ^-5 To
After exhausting until reaching rr, an argon gas was introduced to make an argon atmosphere. After that, the annealing chamber is heated at a temperature rising rate of 5 ° C./minute to a predetermined cooling start temperature T _a1 or T _b1 (° C.), respectively, as shown in Table 3, and at that temperature as shown in Table 3. After holding for a predetermined time t (hr), at a predetermined cooling rate v (° C./min), a predetermined cooling end temperature T
_It was rapidly cooled to _a2 or _Tb2 (° C) and then left to cool.

After that, each laminated body was moved to a sputtering chamber, and a carbon protective layer was laminated at 300 angstrom at a rate of 200 angstrom / minute to obtain a magnetic recording medium. The coercive force and residual magnetization of the obtained magnetic recording medium are
As is clear from the description in Table 3, the holding force (Hc) is 18
10 to 2100 (Oe), remanent magnetization (Mr) is 485 to
A large value of 535 emu / cc was obtained, and a good result was obtained. That is, it was found that the magnetic recording media obtained in Examples 7 to 10 could be applied to high density recording.

[0033]

[Table 3] In Examples 7 to 10, a higher holding force than Examples 1 to 6 is obtained as compared with aluminosilicate glass.
It is considered that a large inverse magnetostriction effect can be obtained because the coefficient of thermal expansion of quartz glass is small.

(Examples 11 to 13) After setting a soda lime glass substrate in the sputtering chamber, the chamber was set at 4 × 10 ^-7 T.
Exhausted until reaching orr. Subsequently, Ar gas was introduced. At this time, the Ar gas pressure was 10 mTorr. A Cr nonmagnetic layer as a base layer was laminated on a glass substrate at a rate of 350 Å / min to 2000 Å by sputtering, and a CoCrTa ferromagnetic layer (Co / Cr / Ta = 84 /) as a recording layer was formed thereon.
14/2) 50 at a speed of 450 angstroms / minute
0 angstrom was laminated, and a Cr nonmagnetic material layer was further laminated thereon as a protective layer at 100 angstrom at a speed of 350 angstrom / min. In this way, three laminated bodies having a three-layer structure were obtained on the substrate.

These laminates are moved to an annealing chamber,
In order to prevent the recording layer from being oxidized, the degree of vacuum in the chamber is 2 × 10 ^-5 To
After exhausting until reaching rr, nitrogen gas was introduced to make a nitrogen atmosphere. After that, the annealing chamber is heated at a heating rate of 5 ° C /
In minutes, the temperature is raised to a predetermined cooling start temperature T _a1 or T _b1 (° C.) as shown in Table 4, respectively, and as shown in Table 4,
After holding at that temperature for a predetermined time t (hr), at a predetermined cooling rate v (° C./min), a predetermined cooling end temperature T _a2 or T
_It was rapidly cooled to _b2 (℃) and then left to cool.

Thereafter, each laminated body was moved to a sputtering chamber, and a carbon protective layer was laminated at a rate of 200 angstrom / min to 300 angstrom to obtain a magnetic recording medium. The coercive force and residual magnetization of the obtained magnetic recording medium are
As is clear from the description in Table 4, the holding force (Hc) is 14
40-1876 (Oe), remanent magnetization (Mr) is 508-
A good value was obtained with a large numerical value of 680 emu / cc. That is, it was found that the magnetic recording media obtained in Examples 11 to 13 could be applied to high density recording.

[0037]

[Table 4] (Examples 14 to 16) After setting the quartz glass substrate in the sputtering chamber, the inside of the sputtering chamber was evacuated until it reached 4 × 10 ^-7 Torr. Subsequently, Ar gas was introduced. A at this time
The r gas pressure was 10 mTorr. A Cr non-magnetic layer is formed on the glass substrate as a base layer by sputtering.
2000 angstroms were laminated at a speed of 0 angstrom / minute, and a CoPtCr ferromagnetic layer (Co / Pt / Cr = 77/6/17) was laminated thereon as a recording layer at a speed of 400 angstroms / minute. Further, a Cr non-magnetic material layer as a protective layer was laminated thereon at 100 angstrom at a rate of 350 angstrom / minute. In this way, 3 having a three-layer structure
Individual laminates were obtained.

These laminated bodies were moved to the annealing chamber,
In order to prevent the recording layer from being oxidized, the degree of vacuum in the chamber is 2 × 10 ^-5 To
After evacuating until reaching rr, the annealing chamber was heated at a temperature rising rate of 5 ° C./minute to a predetermined cooling start temperature T _a1 or T _b1 (° C.), respectively, as shown in Table 5. As shown, after holding at that temperature for a predetermined time t (hr), at a predetermined cooling rate v (° C / min), a predetermined cooling end temperature T _a2
Alternatively, it was rapidly cooled to T _b2 (° C.) and then left to cool.

After that, each laminated body was moved to a sputtering chamber, and a carbon protective layer was laminated at 300 angstrom at a rate of 200 angstrom / minute to obtain a magnetic recording medium. The coercive force and residual magnetization of the obtained magnetic recording medium are
As is clear from the description in Table 5, the holding force (Hc) is 16
05-2130 (Oe), remanent magnetization (Mr) 623-
A good value was obtained with a large numerical value of 733 emu / cc. That is, it was found that the magnetic recording media obtained in Examples 1 to 6 could be applied to high density recording.

[0040]

[Table 5] (Comparative Examples 1 to 6) For comparison, four laminates (Comparative Examples 1 to 4) obtained in the same manner as in Examples 1 to 6 and Examples 11 to 11 were used.
One laminated body obtained in the same manner as 13 (Comparative Example 5) and four laminated bodies obtained in the same manner as Examples 14 to 16 (Comparative Example 6) are shown in Table 6, respectively. The cooling start temperature T _a1 or T _b1 (° C.), the cooling rate v (° C. /
Min), and the cooling treatment was performed by changing the cooling end temperature T _a2 or T _b2 (° C.). It should be noted that, as in the example, the temperature was cooled to room temperature from the cooling end temperature T _a2 or T _b2 (° C.).

Thereafter, each laminated body was moved to a sputtering chamber, and a carbon protective layer was laminated at a rate of 200 Å / min to 300 Å to obtain a magnetic recording medium. The coercive force (Hc) and the residual magnetization (Mr) of the obtained magnetic recording medium were measured in the same manner as in the example. As a result, as is clear from the description in Table 6, the cooling rate was 5 ° C /
In Comparative Example 1 which is slower than the above, the holding power (Hc) is 945 (Oe)
In Comparative Example 2 in which the cooling start temperature is low, the holding power (Hc) was also small as 920 (Oe). Furthermore, in Comparative Example 3 in which the cooling start temperature is too high, the residual magnetization (Mr)
Was 90 emu / cc, which was extremely small. Even in Comparative Example 4 in which the cooling end temperature is higher and Comparative Examples 5 and 6 in which the difference between the cooling start temperature and the cooling end temperature is small, the holding forces (Hc) are 970 (Oe) and 870, respectively.
(Oe) and 950 (Oe) were small. That is, it was found that the magnetic recording media obtained in Comparative Examples 1 to 6 could not support high density recording.

[0042]

[Table 6] Although the sputtering chamber and the annealing chamber are separately provided in the above-described embodiments, the annealing can be performed in the sputtering chamber if the temperature can be controlled in the sputtering chamber. In addition, the temperature at the time of sputtering is 3
The temperature may be the same as the cooling start temperature of 00 ° C. or higher, and the temperature may be rapidly cooled from this temperature.

The ferromagnetic Co-containing alloy used for the recording layer is not limited to the above-mentioned examples, but Co-containing alloys such as Co-M alloys (where M is Ni, Cr, Pt,
Any material containing at least one element selected from Ta and B) may be used. The recording layer may be made of only a ferromagnetic material, and the ferromagnetic material is a main component and other materials (for example, Cr, Pt, Ta, B, W, Zr, P).
Of at least one element selected from the above).

Further, the underlayer and the protective layer are not limited to those described above, and are nonmagnetic materials such as Si, Al, Ti, Bi and V.
n, Mn, Sn, Zn, Ge, Pb, In, Cu, M
It may be n, W, Ni or the like, or alloys thereof.

The holding time is not limited to that of the embodiment, and may be any time as long as the laminate can be kept within a predetermined temperature.

[0046]

As described above, according to the present invention, a metal recording layer containing a ferromagnetic material having a coefficient of thermal expansion larger than that of the substrate is laminated on the substrate directly or via an underlayer. By including a step of cooling the body from a cooling start temperature T _a1 of 300 ° C. to 450 ° C. to a temperature T _a2 of 150 ° C. or lower at an average rate of 10 ° C./min or more, or directly or on the substrate. From the cooling start temperature T _b1 of 450 ° C. to 700 ° C., the above-mentioned cooling start is performed on the stacked body in which the metal recording layer containing the ferromagnetic material having the thermal expansion coefficient larger than that of the substrate is stacked via the formation layer. Provided is a method for producing a magnetic recording medium having a high holding power and capable of coping with high density recording by including a step of cooling at a rate of 10 ° C./min or more on average to a temperature T _b2 lower than the temperature by 300 ° C. or less. I was able to.

Claims (4)

[Claims] 1. A laminate in which a metal recording layer containing a ferromagnetic material having a coefficient of thermal expansion larger than that of the substrate is laminated on a substrate directly or via an underlayer at 300 ° C.
450 from the temperature T _a1 of ° C., to 0.99 ° C. below the temperature T _a2, a method of manufacturing a magnetic recording medium which comprises a step of cooling at an average 10 ° C. / min or faster. 2. A laminated body in which a metal recording layer containing a ferromagnetic material having a thermal expansion coefficient larger than that of the substrate is laminated on a substrate directly or via an underlayer at 450 ° C.
From temperature T _{b1 of up} to 700 ° C., 300 ° C. from the temperature T _b1
A method of manufacturing a magnetic recording medium, comprising a step of cooling to a temperature as low as above T _b2 at an average rate of 10 ° C./minute or more. 3. The method of manufacturing a magnetic recording medium according to claim 1, wherein the substrate is made of glass or ceramic. 4. The Co-M alloy (M is N
At least 1 selected from i, Cr, Pt, Ta, and B
The magnetic recording medium manufacturing method according to claim 1, wherein the magnetic recording medium is selected from the following.