JP3733428B2 - Magnetic cluster, magnetic recording medium, method for manufacturing magnetic cluster, and method for manufacturing magnetic recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic cluster, a magnetic recording medium, a method for manufacturing a magnetic cluster, and a method for manufacturing a magnetic recording medium, which can be suitably used as a minimum magnetic memory and an electron transmission wire in a nanoelectronic ultrafine electronic device. .
[0002]
[Prior art]
In the field of ultrafine electronic devices based on nanotechnology, as conductive nanodevices, integrated rod-like compounds obtained by laminating carbon nanotubes or porphyrin compounds produced by discharge or the like have been developed. However, there is a major problem with how such devices are coupled to other elements.
[0003]
On the other hand, as a magnetic memory, there are used particles in which fine particles made of various inorganic compounds containing a transition metal atom are dispersed in a predetermined matrix, and by reducing the size of the fine particles, the magnetic Attempts have been made to increase the capacity of the memory. Actually, magnetic memories in which manganese or iron oxygen compound clusters are dispersed have been developed. However, these magnetic memories have insufficient spin inversion block temperatures and are not practical.
[0004]
The present invention relates to a novel magnetic cluster, a magnetic recording medium using the same, and a magnetic recording medium that can be suitably used as a conductive nanodevice and a magnetic memory in the field of ultrafine electronic devices based on nanotechnology. It is an object of the present invention to provide a manufacturing method and a manufacturing method of the magnetic recording medium.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention relates to a magnetic cluster having a molecular formula of (CoC ₂ ) _x (X is a natural number) having a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co—C ₂ —Co bond. The magnetic cluster can exist alone, or can exist as a textured structure formed by combining a plurality of magnetic clusters due to a manufacturing method as described below.
[0006]
As a result of intensive studies to achieve the above object, the present invention succeeded in producing a novel magnetic cluster as described above. The unit cell constituting the above-described magnetic cluster, that is, a magnetic cluster having a molecular formula of (CoC ₂ ) _x (X is a natural number) having a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co—C ₂ —Co bond, It has a large spin quantum number per unit volume. Moreover, it has a large anisotropy by exhibiting a tetragonal skeleton structure.
[0007]
Moreover, the size of the magnetic cluster can be set to the nm order by appropriately adjusting the manufacturing conditions. As a result, the magnetic cluster has a sufficiently high block temperature, and can be used as a practical magnetic memory in the field of ultrafine electronic devices. When used as an actual magnetic memory, as shown below, a predetermined magnetic recording medium in which the above-described nm-order magnetic clusters are dispersed in a predetermined matrix is manufactured, and this magnetic recording medium is used as a magnetic memory. Used as
[0008]
Further, the above-mentioned nm order magnetic cluster can be easily coupled with other elements, and therefore can be used as a magnetic conductor in the field of ultrafine electronic devices.
[0009]
The magnetic cluster described above has a ferrimagnetic property at a temperature of 7K or less in a mixed state with cobalt chloride. Further, it has at least one of ferromagnetic and superparamagnetic properties in a greenhouse. Moreover, it has a coercive force of about 250 Gauss or more at the low temperature and room temperature as described above.
[0010]
In the magnetic cluster of the present invention, a hydrogen atom, a halogen atom such as fluorine and chlorine, or a hydrocarbon group may be bonded to the cluster particle interface to stabilize the skeleton atom outside the skeleton.
[0011]
Other features of the magnetic cluster and the magnetic recording medium of the present invention, and the magnetic cluster manufacturing method and the magnetic recording medium manufacturing method of the present invention will be described in detail in the following embodiments of the present invention.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In order to put the magnetic cluster of the present invention into practical use as a magnetic memory in the field of ultrafine electronic devices, it is necessary to grow the magnetic cluster to the order of nm as described above. Specifically, the magnetic cluster is a magnetic cluster having a molecular formula of (CoC ₂ ) _x (X is a natural number) having a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co—C ₂ —Co bond, It is preferable that the length is 3 nm or more and the diameter is 0.8 nm or more.
[0013]
Note that the magnetic cluster can exist alone, or can exist as a textured structure formed by bonding a plurality of magnetic clusters due to the following production method. The textured body preferably has an average particle size of 12 nm or less. Even a magnetic cluster larger than this is not preferable because it exceeds the range required for a magnetic memory in the field of ultrafine electronic devices.
[0014]
When the magnetic cluster of the present invention is used as a magnetic memory in the field of ultrafine electronic devices, the magnetic cluster is dispersed in a predetermined matrix as described above. The matrix is preferably mixed with a substance such as a cobaltcene derivative having paramagnetism such as cobaltcene or bicobaltene, or a ferrocene derivative having diamagnetism such as ferrocene or biferrocene. As a result, the remanent magnetization of the magnetic cluster is increased, and the magnetic characteristics of the magnetic memory are improved.
[0015]
For example, the magnetic cluster of the present invention is a method using light irradiation as shown below (
The first method) and a method using heat treatment (second method) can be used. In any case, a cobalt carbonyl compound and dichloromethane are mixed to prepare a dichloromethane solution in which the cobalt carbonyl compound is dissolved, and the dichloromethane solution is subjected to ultraviolet light or appropriate heat treatment, whereby a photochemical reaction or a reaction is performed. The target magnetic cluster of the present invention is obtained by releasing carbon monoxide (CO) from the dichloromethane solution through a thermochemical reaction.
[0016]
As the cobalt carbonyl compound, Co ₄ (CO) ₁₂ or Co ₂ (CO) ₈ can be used. Furthermore, a carbonyl compound having a larger number of cobalt atoms than Co ₄ (CO) ₁₂ can be used by performing a predetermined reaction in a CO atmosphere.
[0017]
FIG. 1 is a diagram schematically showing the configuration of an apparatus used in the first method. In the apparatus shown in FIG. 1, the above-described dichloromethane solution 6 is placed in a dropping funnel 8 and is dropped as needed into a pressure-resistant glass container 5 sealed with a vacuum glass flange 4. In addition, the dichloromethane solution 6 can be previously stored in the glass container 5 without using the dropping funnel 8.
[0018]
From the lamp light source 1, ultraviolet rays are introduced into the glass container 5 through the condenser lens 2 and the light introduction window 3 and irradiated onto the dichloromethane solution 6. At this time, the dichloromethane solution 6 is remarkably stirred by a rotor 7 provided at the bottom of the glass container 5, for example, a rotating magnet covered with Teflon (registered trademark). Note that CO released during the reaction is discharged to the outside through the cock 9.
[0019]
After the predetermined time has elapsed, the solution remaining in the glass container 5 is filtered with a predetermined filter and sufficiently washed, whereby the magnetic cluster of the present invention exhibiting a blackish brown color can be obtained.
[0020]
The size of the magnetic clusters, depending on the concentration of the dichloromethane solution of cobalt carbonyl compounds, 10 - in the ^{4 to 10} -5 ^M concentration, only the blocking temperature is less magnetic cluster 4K is produced. However, as the concentration increases, the size of the magnetic cluster increases. When a 500 W ultrahigh pressure mercury lamp is used as the lamp light source 1, superparamagnetic magnetism of the order of nm is obtained by irradiation for about 60 minutes or more. Clusters can be created.
[0021]
FIG. 2 is a diagram schematically showing a configuration of an apparatus used for the second method. In the apparatus shown in FIG. 2, a Teflon (registered trademark) container 13 is provided in a hermetic pressure-resistant stainless steel container 14 fastened from above and below by a flange 15, and a glass tube 12 is provided in the container 13. The above-described dichloromethane solution 6 is placed in the glass tube 12 provided. A glass plate suspension 19 is provided at the bottom of the glass tube 12, and a plurality of glass plates 20 are supported by the glass plate hangings 19 and immersed in the dichloromethane solution 6.
[0022]
Argon gas is introduced into the stainless steel container 14 from the argon introduction tube 11, and the inside of the container 14 is replaced with argon gas. At this time, water is prevented from remaining in the container 14 as much as possible. Thereafter, the dichloromethane solution 6 is heated to 200 ° C. or higher, for example, to about 210 ° C. by the heater 16 provided so as to cover the outside of the stainless steel container 14, and is held for a predetermined time, for example, about 10 minutes to 4 hours. The particle size is determined by this holding time. At this time, CO released by the thermochemical reaction is discharged to the outside through the exhaust pipe 17. The pressure in the series of reactions is monitored by a pressure gauge 18 provided at the top of the stainless steel container 14.
[0023]
After a predetermined time has elapsed, the heater 16 is removed, and the residual solution in the stainless steel container 14 is cooled with a fan. Then, the magnetic cluster of the present invention precipitated in the amorphous carbon matrix on the surface of the glass plate 20 can be obtained. Cobalt chloride in this is washed away with purified water. Preferably, after the washed product is pulverized and degassed under dry conditions, it is further dehydrated using purified methanol and powdered to provide the magnetic cluster of the present invention.
[0024]
The size of the magnetic cluster can be controlled by adjusting the heating time at 210 ° C., and becomes smaller as the heating time becomes longer. It also depends on the concentration of the cobalt carbonyl compound in dichloromethane.
[0025]
Before heating the dichloromethane solution 6 to 200 ° C. or higher, it is preferable to heat it to about 100 ° C. and hold it for about 1 hour, and then heat it to, for example, 210 ° C. to cause the thermochemical reaction as described above. In this case, the yield of the magnetic cluster of the present invention from the dichloromethane solution 6 is increased.
[0026]
Further, in the magnetic recording medium including the magnetic cluster of the present invention, after preparing the magnetic cluster as described above, a predetermined matrix material is added to the solution including the magnetic cluster, and the magnetic cluster, the matrix material, To be co-precipitated. According to such a method, the magnetic cluster is dispersed in the matrix, and the intended magnetic recording medium of the present invention can be produced.
[0027]
Specifically, the matrix substance can be directly added to the glass reaction vessel 5 or the solution remaining in the glass tube 12 shown in FIG. Further, the produced magnetic cluster is dissolved in dehydrated methanol, and further filtered and dried. Thereafter, the mixture is uniformly mixed with the matrix substance in an argon stream in a mortar, again dispersed and dissolved in a dichloromethane solution by ultrasonic waves, and coprecipitated from the filtrate, thereby obtaining the intended magnetic recording medium. . The magnetic clusters can be dispersed alone in the matrix, or a plurality of the magnetic clusters can be combined and exist as a textured body.
[0028]
As described above, the matrix material is preferably mixed with a paramagnetic cobalt cene derivative such as cobalt cene or bicobaltene, or a ferrocene derivative such as ferrocene or biferrocene.
[0029]
FIG. 3 shows a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co—C ₂ —Co bond (CoC ₂ ) _x in an amorphous carbon matrix produced using the second method and purified by washing with water. It is a graph which shows the temperature-magnetization curve of a magnetic cluster texture with an average particle diameter of 12 nm which has a molecular formula (X is a natural number). As is clear from FIG. 3, it shows symmetrical behavior when cooled by applying a 10 Oee magnetic field and when cooled by zero magnetic field, and each nanoparticle interacts as a magnetic dipole even at room temperature. It turns out that the magnet which does is comprised.
[0030]
FIG. 4 is a hysteresis curve at 1.8 K of the magnetic cluster obtained by using the first method, and FIG. 5 is a graph showing 20 K of the magnetic cluster in amorphous carbon obtained by using the second method. And a hysteresis curve at 300K. The concentration of magnetic clusters in the latter sample is adjusted to approximately 10%. As is apparent from FIGS. 4 and 5, the magnetic cluster of the present invention exhibits a unique feature that the holding force increases slightly as the temperature increases.
[0031]
FIG. 6 is a graph showing a hysteresis curve of a magnetic cluster produced using the above-described second method and not purified with water. The magnetic cluster used for the measurement is a textured body having an average particle diameter of 12 nm. As is apparent from FIG. 6, when cobalt chloride is contained, when measured at 1.8 K, the magnetization does not tend to saturate even when the applied magnetic field is increased, and the ferrimagnetic properties are not observed. It can be seen that The same tendency was obtained even when the measurement temperature was increased to 7K.
[0032]
On the other hand, when measured at 300 K near room temperature, although the saturation magnetization is small, it can be seen that it exhibits a mixture property of ferromagnetic clusters and superparamagnetic clusters.
[0033]
Further, in both cases of 1.8K and 300K, the holding force was about 250 Gauss, but a holding force of 500 Gauss or more was observed by suppressing the rotation of the particles.
[0034]
FIG. 7 is a graph showing a magnetization-temperature curve when the upper limit of the heating temperature is changed to 150 ° C. and 210 ° C. and the reaction is performed for 6 hours in the second method. The concentration of particles is one digit or more lower than that of the sample shown in FIG. As is apparent from FIG. 7, when the heating temperature is 210 ° C., the magnitude of the magnetization on the high temperature side as a whole is higher than that when the heating temperature is 150 ° C., and the ferromagnetism has a high magnetic susceptibility. It can be seen that more components are produced.
[0035]
As mentioned above, the present invention has been described according to the embodiments of the present invention by showing specific examples. However, the present invention is not limited to the above contents, and all modifications and changes can be made without departing from the scope of the present invention. It can be changed.
[0036]
【The invention's effect】
As described above, according to the present invention, a novel magnetic cluster that can be suitably used as a conductive nanomagnetic device and a magnetic memory in the field of ultra-fine electronic devices based on nanotechnology, and used for this. A magnetic recording medium, a method for manufacturing the magnetic cluster, and a method for manufacturing the magnetic recording medium can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing the configuration of an apparatus used for a first method (using light irradiation).
FIG. 2 is a diagram schematically showing a configuration of an apparatus used for a second method (use of heat treatment).
FIG. 3 is a graph showing a temperature-magnetization curve of a sample (particle concentration of about 10%) produced by the second method.
FIG. 4 is a hysteresis curve at 1.8K of a sample manufactured by the first method.
FIG. 5 is a hysteresis curve at 20K and 300K of a sample manufactured by the second method.
FIG. 6 is a graph showing a hysteresis curve of an unwashed sample containing cobalt chloride prepared by using the second method.
FIG. 7 is a graph showing a magnetization-temperature curve of a magnetic cluster obtained by changing the heating temperature to 150 ° C. and 210 ° C. in the second method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lamp light source 2 Condensing lens 3 Light introduction window 4 Vacuum glass flange 5 Pressure-resistant glass reaction vessel 6 Dichloromethane solution 7 Rotor 8 Drip funnel 9 Cock 11 Argon gas introduction tube 12 Glass tube 13 Teflon (registered trademark) vessel 14 Pressure resistance Stainless steel container 15 Flange 16 Heater 17 Exhaust pipe 18 Pressure gauge 19 Glass plate suspension 20 Glass plate

Claims (39)

A magnetic material having a molecular formula of (CoC ₂ ) _x (X is a natural number) having a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co—C ₂ —Co bond, and having a size on the order of nm. cluster.   The magnetic cluster according to claim 1, wherein the magnetic cluster has a length of 3 nm or more and a diameter of 0.6 nm or more.   The magnetic cluster according to claim 1, wherein the magnetic cluster exhibits a ferrimagnetic property at a temperature of 7 K or less in a mixed state with cobalt chloride. The magnetic cluster is characterized by exhibiting at least one of the properties of ferromagnetic and superparamagnetic at room temperature, magnetic cluster according to any one of claims 1 to 3.   The magnetic cluster according to claim 1, wherein a coercive force of the magnetic cluster is about 250 Gauss or more at room temperature.   A textured structure comprising a plurality of the magnetic clusters according to claim 1 bonded together.   The texture according to claim 6, wherein the average particle diameter is 12 nm or less. A magnetic cluster having a molecular formula of (CoC ₂ ) _x (X is a natural number) having a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co-C ₂ -Co bond and having a size on the order of nm is present in the matrix. A magnetic recording medium characterized by being dispersed.   The magnetic recording medium according to claim 8, wherein the magnetic cluster has a length of 3 nm or more and a diameter of 0.6 nm or more.   The magnetic recording medium according to claim 8, wherein a plurality of the magnetic clusters are combined to form a textured body. The magnetic recording medium according to claim 10, wherein the average particle diameter is 12 nm or less.   The magnetic recording medium according to claim 8, wherein the matrix includes a paramagnetic substance.   The magnetic recording medium according to claim 8, wherein the matrix includes a substance exhibiting diamagnetism. A step of mixing a cobalt carbonyl compound and dichloromethane to form a dichloromethane solution in which the cobalt carbonyl compound is dissolved;
The dichloromethane solution is irradiated with ultraviolet light, and the dichloromethane solution is reacted photochemically to form a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co—C ₂ —Co bond (CoC ₂ ) _x (X is Generating a magnetic cluster having a molecular formula of (natural number) and a size on the order of nm;
A method for producing a magnetic cluster, comprising:   The method of manufacturing a magnetic cluster according to claim 14, wherein the magnetic cluster has a length of 3 nm or more and a diameter of 0.6 nm or more.   16. The method of manufacturing a magnetic cluster according to claim 14, wherein a plurality of the magnetic clusters are combined to form a textured body.   The method of manufacturing a magnetic cluster according to claim 16, wherein an average particle diameter of the texture is 12 nm or less. The method for producing a magnetic cluster according to claim 14, wherein the cobalt carbonyl compound is Co ₄ (CO) ₁₂ or Co ₂ (CO) ₈ . A step of mixing a cobalt carbonyl compound and dichloromethane to form a dichloromethane solution in which the cobalt carbonyl compound is dissolved;
The dichloromethane solution is heated to 200 ° C. or more, and the dichloromethane solution is reacted thermochemically to exhibit a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co—C ₂ —Co bond (CoC ₂ ) _x (X Is a natural number), and a step of generating a magnetic cluster having a size on the order of nm,
A method for producing a magnetic cluster, comprising: A step of mixing a cobalt carbonyl compound and dichloromethane to form a dichloromethane solution in which the cobalt carbonyl compound is dissolved;
Heating the dichloromethane solution to about 100 ° C. and reacting the dichloromethane solution thermochemically for a predetermined time;
The dichloromethane solution is heated to 200 ° C. or higher, and the dichloromethane solution is reacted thermochemically to exhibit a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co—C ₂ —Co bond (CoC ₂ ) _x (X is Generating a magnetic cluster having a molecular formula of (natural number) and a size on the order of nm;
A method for producing a magnetic cluster, comprising:   The method of manufacturing a magnetic cluster according to claim 19 or 20, wherein the magnetic cluster has a length of 3 nm or more and a diameter of 0.6 nm or more.   The method of manufacturing a magnetic cluster according to any one of claims 19 to 21, wherein a plurality of the magnetic clusters are combined to form a textured body.   The method for producing a magnetic cluster according to claim 22, wherein the average grain size of the texture is 12 nm or less. The method for producing a magnetic cluster according to any one of claims 19 to 23, wherein the cobalt carbonyl compound is Co ₄ (CO) ₁₂ or Co ₂ (CO) ₈ . A step of mixing a cobalt carbonyl compound and dichloromethane to form a dichloromethane solution in which the cobalt carbonyl compound is dissolved;
The dichloromethane solution is irradiated with ultraviolet light, and the dichloromethane solution is reacted photochemically to form a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co—C ₂ —Co bond (CoC ₂ ) _x (X is Generating a magnetic cluster having a molecular formula of (natural number) and a size on the order of nm;
Adding a predetermined matrix material to a solution containing the magnetic cluster, and coprecipitation of the magnetic cluster and the matrix material to obtain a magnetic recording medium in which the magnetic cluster is dispersed in the matrix; ,
A method for producing a magnetic recording medium, comprising:   26. The method of manufacturing a magnetic recording medium according to claim 25, wherein the magnetic cluster has a length of 3 nm or more and a diameter of 0.6 nm or more.   27. The method of manufacturing a magnetic recording medium according to claim 25, wherein a plurality of the magnetic clusters are combined to form a textured body.   28. The method of manufacturing a magnetic recording medium according to claim 27, wherein an average particle diameter of the texture is 12 nm or less. The method of manufacturing a magnetic recording medium according to any one of claims 25 to 28, wherein the cobalt carbonyl compound is Co ₄ (CO) ₁₂ or Co ₂ (CO) ₈ .   30. The method of manufacturing a magnetic recording medium according to claim 25, wherein the matrix material exhibits paramagnetism.   30. The method of manufacturing a magnetic recording medium according to claim 25, wherein the matrix material exhibits diamagnetism. A step of mixing a cobalt carbonyl compound and dichloromethane to form a dichloromethane solution in which the cobalt carbonyl compound is dissolved;
The dichloromethane solution is heated to 200 ° C. or more, and the dichloromethane solution is reacted thermochemically to exhibit a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co—C ₂ —Co bond (CoC ₂ ) _x (X Is a natural number) having a molecular formula and producing a magnetic cluster having a size on the order of nm,
Adding a predetermined matrix material to the solution containing the magnetic clusters, and coprecipitation of the magnetic clusters and the matrix to obtain a magnetic recording medium in which the magnetic clusters are dispersed in the matrix;
A method for producing a magnetic recording medium, comprising: A step of mixing a cobalt carbonyl compound and dichloromethane to form a dichloromethane solution in which the cobalt carbonyl compound is dissolved;
Heating the dichloromethane solution to about 100 ° C. and reacting the dichloromethane solution thermochemically for a predetermined time;
The dichloromethane solution is heated to about 200 ° C. or more, and the dichloromethane solution is reacted thermochemically to exhibit a (CoC ₂ ) ₄ tetragonal skeleton structure having a Co—C ₂ —Co bond (CoC ₂ ) _x ( A step of generating a magnetic cluster having a molecular formula (X is a natural number) and a size on the order of nm;
Adding a predetermined matrix material to the solution containing the magnetic clusters, and coprecipitation of the magnetic clusters and the matrix to obtain a magnetic recording medium in which the magnetic clusters are dispersed in the matrix;
A method for producing a magnetic recording medium, comprising:   34. The method of manufacturing a magnetic recording medium according to claim 32, wherein the magnetic cluster has a length of 3 nm or more and a diameter of 0.6 nm or more.   The method of manufacturing a magnetic recording medium according to any one of claims 32 to 34, wherein a plurality of the magnetic clusters are combined to form a textured body.   36. The method of manufacturing a magnetic recording medium according to claim 35, wherein an average particle diameter of the texture is 12 nm or less. The cobalt carbonyl compound is characterized by a Co ₄ (CO) ₁₂ or Co ₂ (CO) _8, a manufacturing method of a magnetic recording medium according to any one of claims 32 to 36.   The method of manufacturing a magnetic recording medium according to any one of claims 32 to 37, wherein the matrix material exhibits paramagnetism.   38. The method of manufacturing a magnetic recording medium according to claim 32, wherein the matrix substance exhibits diamagnetism.

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