JPH05253466A - Production of magnetic anisotropic thin film - Google Patents

Abstract

PURPOSE:To obtain a thin film high in magnetic anisotropy by introducing a planer complex compound into a multilayer bimolecular thin film of an amphiphilic material high in bimolecular film forming ability by utilizing ion exchange reactivity. CONSTITUTION:A spreading solution of the amphiphilic material having bimolecular film forming ability is spread on a substrate, a solvent is removed step by step from the formed liquid film and the multilayer bimolecular thin film is formed. The multilayer bimolecular thin film is brought into contact with a solution of the planer ionic complex compound. The complex compound is introduced into the inner part of the multilayer bimolecular thin film by ion exchange reaction, is fixed and the thin film excellent in magnetic anisotropy reflected by high two dimensionally oriented anisotropy of the multilayer bimolecular thin film is obtained. The thin film obtained in this way is used as an organic magnetic material in a wide field such as magnetic recording material, magnetic recording medium, electromagnetic wave absorbent or electromagnetic conversing element by utilizing magnetic anisotropy or machinability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thin film having a high magnetic anisotropy in which a complex compound having a magnetic moment is regularly arranged at the molecular level.

[0002]

2. Description of the Related Art Utilizing a complex compound of a transition metal ion,
Various attempts have hitherto been made to synthesize organic magnetic materials. For example, by utilizing magnetic interaction between transition metals, a complex compound having a ligand that arranges a plurality of transition metal ions of the same kind or different kinds in a specific positional relationship is synthesized. It is also known that complex compounds are regularly arranged in order to control magnetic interaction between transition metal ions and complex compounds.

As a matrix for regularly arranging complex compounds, the structure of a bilayer membrane assembly, which is stable and ordered at the molecular level, similar to a biological membrane formed by a certain type of amphiphile is used. There is. In particular, the multilayer bilayer thin film obtained by spreading the amphipathic substance developing solution on the substrate, removing the solvent from the formed liquid film, and drying it should be a film with self-supporting properties. It has the advantage of being easy to handle. Further, the bilayer film layer plane is spread in parallel to the thin film surface and stacked, and has a multilayer bilayer film structure having a high level of two-dimensional orientation anisotropy and regular at the molecular level. This structure is effective for the regular arrangement and arrangement of complex compounds.

It is expected that a thin film having high magnetic anisotropy will be obtained when the complex compound is two-dimensionally arranged by utilizing the molecular organization of the amphipathic substance capable of forming a bilayer film. For example, JP-A-62-281310 introduces a combination of a complex compound composed of a ligand having a special molecular structure and a specified amphipathic substance capable of forming a bilayer film. In addition, Journal of America
n Chemical Society, vol. 113
(1991) pp. 621-630, a developing solution containing both an amphipathic substance capable of forming a bilayer membrane and a complex compound having an ionic planar structure is prepared. It has been introduced to make a functional thin film. All of these are methods in which a complex compound is added together with a developing solution of an amphipathic substance capable of forming a bilayer film.

[0005]

When a complex compound is added to a developing solution of an amphipathic substance, the prepared developing solution is spread on a substrate, and a solvent is removed from the formed liquid film to obtain a multilayer structure. The bilayer thin film is very brittle and has a small piece shape, and is inferior in thin film forming ability. Further, the magnetic anisotropy of the thin film itself is not so large. Moreover, when the addition amount of the complex compound is increased, both the thin film forming ability and the magnetic anisotropy sharply decrease.

When the thin film forming ability and the magnetic anisotropy are lowered, the complex compound added in advance acts as an interfering component when forming a multilayer bilayer thin film from an amphipathic compound by spreading on a liquid film and removing the solvent. It is presumed that the cause is that it works and inhibits the molecular organization of amphipathic substances. fact,
When the X-ray diffraction pattern was measured, the two-dimensional orientation anisotropy of the amphipathic substance with respect to the thin film surface in the multilayer bilayer membrane thin film prepared from the developing solution containing the complex compound contained only the amphipathic substance. It is lower than the thin film prepared from the developing solution. From this, it is considered that the obtained thin film has low magnetic anisotropy.

Therefore, in order to effectively use the high two-dimensional orientation anisotropy of a multilayer bilayer thin film formed by an amphipathic substance as a matrix and produce a thin film excellent in magnetic anisotropy, a complex compound is required. A method that can maintain the high two-dimensional orientation anisotropy of amphiphiles even in the system containing a compound, a complex compound is introduced into the thin film while maintaining the two-dimensional orientation anisotropy of a multilayer bilayer membrane. A method to do so is required.

The present invention has been devised to satisfy such requirements, and by bringing the produced multilayer bilayer membrane thin film into contact with a complex compound having a charge, a two-dimensional orientation anisotropy is obtained. The purpose is to introduce a complex compound into the matrix of a high multilayer bilayer thin film with good regularity to obtain a thin film excellent in magnetic anisotropy.

[0009]

In order to achieve the object, a method for producing a magnetic anisotropic thin film according to the present invention, in order to achieve the object, after developing a developing solution of an amphipathic substance capable of forming a bilayer film on a substrate,
Making a multilayer bilayer membrane thin film of the amphipathic substance by removing the solvent from the liquid film formed on the substrate,
The multilayer bilayer thin film is brought into contact with a solution containing a complex compound having a positive or negative charge. A compound having an ionic hydrophilic group is used as the amphipathic substance. The complex compound is preferably a substance having a planar coordination structure.

When a developing solution of an amphipathic substance to which a complex compound is added is used, a multilayer bilayer membrane having high two-dimensional orientation anisotropy cannot be obtained as described above. Therefore, a developing solution is prepared only with an amphipathic substance containing no complex compound, and a multilayer bilayer thin film is first produced from this developing solution. Then
By utilizing the ion exchange property of the multilayer bilayer membrane thin film, the multilayer bilayer membrane thin film is brought into contact with a solution containing a complex compound having a positive or negative charge to introduce the complex compound into the thin film.

By taking the two steps of producing the multi-layered bilayer thin film and introducing the complex compound in this way, the two-dimensional orientation anisotropy of the multi-layered bilayer thin film is utilized and the introduced complex is introduced. The sequence regularity of the compound is also improved. However, since the introduction of the complex compound depends on the ion exchange reaction, the usable complex compound is specified to have a positive or negative charge.
On the other hand, as for the amphipathic substance forming the multilayer bilayer thin film, the polar group of the hydrophilic part is selected in consideration of the ion exchange property with the complex compound.

The combination of the complex compound and the amphipathic substance will be specifically described in Examples. For complex compounds having a negative charge, an ion pair type amphiphile such as an ammonium salt having a positively charged residue is used. As for the complex substance having a positive charge, an amphipathic substance having an acid such as a phosphoric acid group or a salt thereof as a polar group is preferable. Regarding the hydrophobic groups of amphiphiles,
There is no particular limitation as long as it has a chemical structural feature capable of forming a bilayer film.

The chemical structural characteristics of the amphipathic substance having the ability to form a bilayer film and the reason why the thin film forming ability is high by this, typical compound examples, the developing solution preparation method, and the developing solution on the substrate. For a method for producing a multilayer bilayer membrane thin film by removing the solvent from the liquid film formed by the method described in Japanese Patent Application No.
As described in detail in the specification such as 58889,
It is omitted here. Further, the compound, the preparation method, the multilayer bilayer thin film preparation method and the like introduced in Japanese Patent Application No. 1-58889 can be used in the present invention.

The complex compound used is oriented and fixed in the two-dimensional space of a multi-layered bilayer thin film made of an amphipathic substance, and causes magnetic anisotropy on the thin film surface. From this, a complex compound having a planar molecular structure is preferable. Specifically, there are a complex compound composed of a cyclic planar ligand such as porphyrin and phthalocyanine, and a complex compound having a plane four-coordinated structure with copper, vanadium and the like as a central metal. This complex compound has an ion exchange property with the multilayer bilayer membrane,
It is necessary to have positively or negatively charged polar groups.

An example of the complex compound used is a porphyrin compound TPPS of the following formula as a cyclic planar ligand.
(1) and TMPyP (2).

[0016]

[Chemical 1]

Further, examples of the coordination compound which forms a plane four-coordination type complex compound with copper ions or the like include Tyrone Tiron (3) and Zincon Zincon (4) of the following formulae.

[0018]

[Chemical 2]

In the contact treatment operation of the complex compound and the amphipathic substance with the multilayer bilayer membrane thin film, the complex compound is preferably water-soluble in consideration of the solubility of the amphipathic substance in the organic solvent. .. Further, the water-soluble complex compound facilitates the contact treatment operation when used as an aqueous solution system.

As the contact treatment method, a method of dropping a complex compound solution onto a multilayer bilayer membrane thin film of an amphipathic substance can be adopted, but in consideration of operability, a solution containing the complex compound is added to the multilayer bilayer membrane. The method of immersing the thin film is simple.

The ion exchange reaction between the multi-layered bilayer thin film of the amphipathic substance and the complex compound solution easily proceeds even at room temperature. Therefore, the concentration of the complex compound solution is not limited by the ion exchange reaction. The amount of the complex compound introduced into the multi-layered bilayer thin film is affected by the concentration of complex compound solution, temperature, immersion time, etc. by the dipping method, but these reaction conditions are appropriately selected as necessary.

For example, in the case of a combination of a multi-layered bilayer membrane film of an amphipathic substance and a complex compound solution used in Example 1 to be described later, 1 mol / mol of the amphipathic substance is immersed in the complex compound solution at 20 ° C. for 1 week. 20 mol of copper complex compound can be introduced. This amount of introduction corresponds approximately to the amount of copper complex compound laid as a monolayer between the layers of the multilayer bilayer thin film. It is also possible to increase the introduction amount of the complex compound by further dipping for a long time. Further, the introduction amount of the complex compound can be adjusted by separately repeating the contact treatment between the multilayer bilayer membrane thin film and the complex compound solution, including the dipping method, a plurality of times.

The amphipathic multi-layered bilayer membrane thin film in which the complex compound is introduced into the thin film by the contact treatment with the complex compound solution is finally washed with pure water or the like and attached to the thin film surface or the like. After washing away the complex compound and the like, it is air dried. The dried multilayer bilayer membrane thin film becomes a self-supporting film.

[0024]

[Operation] A multilayer bilayer thin film made of an amphipathic substance capable of forming a bilayer has a lamella structure with highly regular two-dimensional planar anisotropy at the molecular level.
When the hydrophilic group of the amphipathic substance is an ion pair type or an ion dissociative type, the counter ion has an ion-exchange property and easily ion-exchanges while maintaining a specific tissue structure, and the hydrophilic part of the hydrophilic part Has the property of incorporating ionic compounds. Utilizing this property, inorganic ions are introduced by ion exchange between the layers of the multilayer bilayer membrane, and the multilayer bilayer membrane is used as a molecular template to form a multilayer inorganic thin film composed of unit thickness layers at the molecular level. Japanese Patent Application No. 2-31
No. 0734 and Japanese Patent Application No. 3-246609. When this inorganic thin film is produced, the ion exchange reaction proceeds while maintaining the multilayer bilayer structure.

In the present invention, utilizing this ion exchange reactivity, a complex compound having a magnetic moment is arranged two-dimensionally at a molecular level regularity between layers of an amphipathic multi-layered bilayer membrane thin film, A thin film having magnetic anisotropy is manufactured. The ESR spectrum of the complex compound taken in the multilayer bilayer thin film was obtained from the developing solution prepared by directly adding the complex compound to the developing solution of the amphipathic substance, as shown in the examples below. The ESR spectrum of the prepared complex compound-containing multi-layered bilayer thin film is basically the same as the ESR spectrum although there is a difference in magnetic anisotropy. Also, regarding complex compounds introduced by the ion exchange method, Journal
al of American Chemical S
ociety, vol. 113 (1991) No. 621-
The layout structure model described on page 630 can be similarly estimated.
That is, the complex compound introduced by the ion exchange reaction is regularly arranged in a state where the molecular plane of the complex compound is parallel or perpendicular to the plane of the thin film layer while maintaining its tissue structure between the hydrophilic portions of the multilayer bilayer membrane. Arranged.

The peculiar ion exchange characteristics of a multilayer bilayer membrane formed by an amphipathic substance capable of forming a bilayer membrane are the stability of the bilayer membrane structure itself and the stability of the lamella-type multilayer bilayer membrane structure,
It is speculated that this is due to the chemical structural characteristics of the amphipathic substance that easily forms the bilayer membrane structure. In contrast,
Ordinary surfactants, which are amphipathic substances that do not have the ability to form bilayer membranes, are not only difficult to form thin films with self-supporting and regular molecular organization structures, but also complex compounds. It does not show ion exchange property.

The amphipathic substance capable of forming a bilayer film is
A molecular assembly composed of a bilayer membrane such as vesicles is formed in the developing solution. This molecular assembly changes into a lamella-type multilayer bilayer structure in the process of developing as a liquid film and removing the solvent. When an ionic complex compound coexists in this process, it is presumed that the structural change to the lamella-type multilayer bilayer membrane is hindered by the electrostatic interaction with the amphipathic substance. As a result, in the thin film prepared from the developing solution of the amphipathic substance to which the complex compound was added, the multilamellar bilayer structure having high lamellar two-dimensional orientation anisotropy did not grow sufficiently and the magnetic anisotropy was increased. It's getting low.

Therefore, in order to sufficiently grow the lamella-type multilayer bilayer membrane structure, an ion-exchange reaction is performed while maintaining a high two-dimensional orientation anisotropy after preparing a multilayer bilayer membrane thin film containing an amphipathic substance alone. A complex compound is introduced by. As a result, a thin film having high magnetic anisotropy reflecting the texture structure of the multilayer bilayer thin film is manufactured.

[0029]

Examples Example 1 : As an amphipathic substance capable of forming a bilayer film, a compound having the structure of the following formula (5) was used.

[0030]

[Chemical 3]

A developing solution was prepared by ultrasonically dispersing the amphipathic substance (5) in pure water at a concentration of 30 mM. The developing solution thus obtained was spread on a fluoropore, and the formed liquid film was left in an atmosphere having a temperature of 25 ° C. and a relative humidity of 60% to gradually remove water in the liquid film by evaporation. as a result,
A self-supporting, film-like, white, semi-transparent, multilayer bilayer membrane was obtained.

Further, by adding an equivalent amount of copper chloride as an aqueous solution to the aqueous solution of the above-mentioned compound (2) at room temperature,
A cationic copper complex compound was prepared. The concentration of the copper complex compound aqueous solution was 0.2 mM. The multi-layered bilayer membrane thin film of the amphipathic substance produced in this copper complex compound aqueous solution was dipped and left for 2 days, and then the multi-layered bilayer membrane thin film was pulled out from the aqueous solution. The contact-treated multilayer bilayer membrane thin film was washed with pure water and air-dried.

The treated multi-layered bilayer thin film had a uniform crimson color and was in the form of a self-supporting film similar to the one before being immersed in the complex compound aqueous solution. The amount of the copper complex compound introduced into the thin film was determined to be 1 mol / 80mo with respect to the amphipathic substance (5) by measuring the absorbance of the UV spectrum.
Calculated as l.

The ESR spectrum of the thin film was measured at room temperature by an electron spin resonance apparatus while changing the angle between the thin film and the applied magnetic field. In FIG. 1 showing the measurement results,
(A) shows an ESR spectrum when the thin film is measured perpendicularly to the applied magnetic field, and (b) shows an ESR spectrum when the thin film is measured parallel to the applied magnetic field.

In FIG. 1A, the parallel component g _// (= 2.2
0), but in FIG. 1B, the vertical component g⊥ (= 2.0
Only 5) is shown. From this, it is understood that the copper complex compound is regularly arranged in the thin film in a state where the porphyrin ring plane is parallel to the thin film surface.

For comparison, a 0.2 mM copper complex compound aqueous solution was frozen at liquid nitrogen temperature, and ESR was performed at room temperature.
The spectrum was measured. As is clear from FIG. 2 showing the measurement result, both the parallel component and the vertical component appear, and the complex compound is in an isotropically dispersed state. From the comparison between FIG. 1 and FIG. 2, it is understood that the thin film manufactured in this example has a large paramagnetic magnetic anisotropy in the thin film surface direction.

Comparative Example 1 : Amphiphilic substance (5) of Example 1
In a 30 mM aqueous dispersion of the above, a copper complex compound of the compound having the structure of formula (3) was added at 1 mol / 1 with respect to the amphipathic substance (5).
The mixture was added at a rate of 000 mol and irradiated with ultrasonic waves again to prepare a uniform developing solution containing a copper complex compound. This developing solution was spread on Fluoropore in the same manner as in Example 1 to evaporate the water to prepare a thin film containing a copper complex compound. The obtained thin film had a deep red color, was brittle, and was easily broken into small pieces.

The ESR spectrum of this thin film had an angle dependence between the thin film and the applied magnetic field as shown in FIG. That is, even when the thin film is placed in parallel with the applied magnetic field, the parallel component g _// (= 2.20) appears considerably strongly. The film-forming property and magnetic anisotropy were significantly inferior to those of Example 1 despite the small amount of the copper complex compound introduced into the thin film.

Example 2 As an amphipathic substance capable of forming a bilayer film, a compound having the structure of the following formula (6) was used.

[0040]

[Chemical 4]

A developing solution was prepared by ultrasonically dispersing the amphipathic substance (6) in pure water at a concentration of 30 mM. Then, by the same operation as in Example 1, a film-like white semi-transparent multilayer bilayer membrane having self-supporting properties was produced.

To the aqueous solution of the porphyrin compound (1), an equivalent amount of copper sulfate was added as an aqueous solution at room temperature to give a concentration of 0.2 mM.
An aqueous solution of anionic copper complex compound was prepared. The multi-layered bilayer membrane thin film of the amphipathic substance (6) was immersed in this copper complex compound aqueous solution, left for one day and night, and then the multi-layered bilayer membrane thin film was pulled out from the aqueous solution. The contact-treated thin film was washed with water and then air-dried.

The thin film in which the copper complex compound was introduced exhibited a uniform brown color and was in the form of a film having self-supporting properties similar to that before being immersed in the copper complex compound aqueous solution. The amount of the copper complex compound introduced into the thin film was determined to be 1 mol / 100 mo with respect to the amphipathic substance (6) by measuring the absorbance of the UV spectrum.
Calculated as l.

FIG. 4 shows the angle dependence of the ESR spectrum of this thin film between the thin film and the applied magnetic field. Similar to the first embodiment, in FIG. 4A when the thin film is perpendicular to the applied magnetic field, only the parallel component g _// (= 2.19) is
In FIG. 4B when the thin film surface is parallel to the applied magnetic field, only the vertical component g⊥ (= 2.06) appears. From this, it is understood that the copper complex compound is regularly arranged in the thin film in a state where the porphyrin ring plane is parallel to the thin film surface. In addition, high paramagnetic anisotropy was exhibited for the thin film surface.

Comparative Example 2 : 1 mol / 100 mo of the copper complex compound of the chemical formula (1) was added to the developing solution of the amphipathic substance (6).
It was added at a rate of 1 l. At this time, ultrasonic waves were irradiated again after adding the copper complex compound, but some turbidity was generated in the developing solution. The developing solution was developed on the fluoropore to form a liquid film, and water was removed from the liquid film by evaporation under the same conditions as in Example 1. The obtained thin film was formed into small pieces, and the angle dependence of the ESR spectrum could not be measured.

[0046]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, a multilayered bilayer membrane of an amphipathic substance capable of forming a bilayer membrane is formed in a molecular assembly having regular hardness at the molecular level. The complex compounds having a planar structure are regularly arranged by utilizing the ion exchange reactivity. The resulting thin film exhibits a good magnetic anisotropy because it is a complex compound in which the anisotropy of orientation is highly ordered. In addition, when applying a complex compound to a magnetic material, there is no restriction on the complex compound that can be used, and an amphipathic substance can be appropriately selected according to the complex compound. An anisotropic thin film is produced. Moreover, since the thin film produced is a film having a self-supporting property, it is easy to handle and has excellent workability. As a novel organic magnetic material, a magnetic recording material, a magnetic recording medium, an electromagnetic wave absorber, a small motor, It is used in a wide range of fields such as transformers and electromagnetic conversion elements.

[Brief description of drawings]

FIG. 1 is an ESR spectrum showing the magnetic anisotropy of the thin film prepared in Example 1.

FIG. 2 ESR spectrum measured at room temperature after freezing the aqueous solution of the copper complex compound used in Example 1 with liquid nitrogen.

FIG. 3 ESR spectrum showing magnetic anisotropy of the thin film prepared in Comparative Example 1.

FIG. 4 is an ESR spectrum showing the magnetic anisotropy of the thin film prepared in Example 2;

Claims (3)

[Claims] 1. A multi-layer of the amphipathic substance by developing a developing solution of an amphipathic substance capable of forming a bilayer film on a substrate and then removing the solvent from the liquid film formed on the substrate. A method for producing a magnetic anisotropic thin film, which comprises producing a bilayer thin film and bringing the multilayer bilayer thin film into contact with a solution containing a complex compound having a positive or negative charge. 2. The method for producing a magnetic anisotropic thin film, wherein the amphipathic substance according to claim 1 has an ionic hydrophilic group. 3. The method for producing a magnetic anisotropic thin film, wherein the complex compound according to claim 1 is a substance having a planar coordination structure.