JPH1032111A - Molecular mixed magnetic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the molecular mixed magnetic material with superior magnetic characteristics as well as a new performance by providing the molecular magnetic material with variable magnetic characteristics from light irradiation. SOLUTION: Fe1.5 Cr(CN)6 as a CN-crosslinking metallic complex is produced by mixing the aqueous solution of Fe2 Cl2 and K3 Cr(CN)6 . The composition formula of this complex as a ferromagnetic body is F1.5 Cr(CN)6 .7.5 H2 O to be face-centered cubic lattice structured. The magnetization of Fe1.5 Cr(CN)6 .7.5 H2 O is reduced by irradiating this complex for several hours at the temperature of about 5K and in exposing to an external magnetic field of about 40G. At this time, a high-pressure mercury lamp is used as a light source for examining the photomagnetic effect. Finally, this complex is annealed up to the temperature of about 70K for restoring the magnetization value to that before the irradiation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molecular mixed magnetic material. More specifically, the present invention relates to a novel molecular magnetic material which can control and design various magnetic properties and is useful as various functional materials such as a magnetic device, a magnetic shield, a sensor, and a motor.

[0002]

2. Description of the Related Art Magnetic materials typified by metals such as iron and metal oxides such as ferrite have been used in various fields. In recent years, these magnetic materials have been replaced by more and more materials. A so-called molecular magnetic material, which can be designed from the molecular level, has attracted attention as a material that may exhibit advanced functions.

[0003] This indicates that molecular materials can be designed in various structures, and that the expectation of molecular magnetic materials is high in combination with the attention to electronic functions or optical functions. I have. However, according to the investigations so far, this molecular magnetic material has just been started, and the properties and structure of these materials remain almost unknown.

Therefore, the present invention has been made in accordance with the great expectation for molecular magnetic materials by overcoming the above technical limitations, and has a new function with excellent magnetic properties. It is intended to provide a molecular magnetic material.

[0005]

According to the present invention, a magnetic ion unit of a molecular magnetic material exhibiting ferromagnetism and a magnetic ion unit of a molecular magnetic material exhibiting ferrimagnetism are each provided to solve the above-mentioned problems. Provided is a molecular mixed magnetic material, which is a molecular magnetic material having at least one or more types and whose magnetic characteristics are variable by light irradiation.

The present invention also relates to a molecular mixed magnetic material which can be changed into a ferromagnetic material and an antiferromagnetic material, as well as a molecule which has variable magnetic characteristics such as saturation magnetization, coercive force, residual magnetization, and magnetic phase transition point. As a mixed magnetic material, a molecular mixed magnetic material in which a magnetic ion unit is a transition metal, and at least a magnetic ion, M ₁ -BM ₂ (M ₁ , M ₂ and B are magnetic ions, and M ₁ and M _Two
Have an exchange interaction (J) with B with J> 0 and J <0 for B), respectively, and have a magnetic ion M ₁
And and molecular mixing magnetic material abundance ratio of M ₂ is controlled,
The present invention is provided as one embodiment of a molecular mixed magnetic material or the like in which the magnetic properties are variable depending on the temperature and the magnetic poles are reversed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the present invention provides a molecular mixed magnetic material which has not been known at all. More specifically, in the case of a normal magnetic material, the magnetization below the Curie point (Tc) monotonically increases with a decrease in temperature. On the other hand, by Nehru,
Specific temperature (compensation point) in the theory of ferrimagnetic material
It has been predicted that there is a magnetic material whose magnetization sign is reversed, and magnetic materials having negative magnetization such as NiFe _2-x V _x O ₄ have been found so far.

Subsequently, the inventors of the present invention have proposed a new methodology in which the superexchange interaction between metals combines a positive one and a negative one, that is, a ferromagnetic interaction (J>
0) and diamagnetic interaction (J <0) to find molecular magnetic materials that can control spontaneous magnetization, Curie temperature, Weiss temperature, coercive force, etc., and enable new technological development. .

For example, (Ni _x Mn _1-x ) _1.5 Cr
In the system of (CN) ₆ , various temperature dependences of magnetization can be obtained, and it can be designed by molecular magnetic field theory. In particular, (Ni _0.38 Mn _0.62 ) _1.5 Cr (CN)
No. ₆ finds that the magnetic pole is inverted and magnetized at 39K or less. It has also been confirmed that this is due to the difference in temperature dependence between the negative magnetization of the Mn ^II sublattice and the positive magnetization of the Ni ^II and Cr ^III sublattices.

That is, its essential features are positive and negative.
And the magnetic properties are variable.
That is being done. Therefore, in the present invention,
Based on these findings, the intersection between this positive and negative spin
We are interested in commutation interactions. That is, for light irradiation
Therefore, electron transfer or spin crossover is
Either the ferro part of the remixed magnetic single crystal is the ferri part
If this happens, the balance of the sublattice magnetization will be lost,
It is thought to change. For example, (A1_xA2_1-x)
_1.5B (CN)₆A1 site of the ferro part of the
Spin crossover with visible light at A2
And the spin quantum numbers of A1, A2, and B are 1, 2, 2,
Assuming that 1.5, A1 (S = 1) to A1
When the spin crossover is performed to (S = 0), the total magnetization (M
_total) Indicates that the positive magnetization of A1 decreases,
Shift to value. On the other hand, A2 (S = 2) to A2 (S =
0), the total magnetization (M
_total) Is positive due to the decrease in the negative magnetization of A2.
Will shift to the value.

FIG. 1 of the accompanying drawings illustrates such (A1)
shows the _x A2 _{1-x) 1.5} magnetization temperature curve before and after the light irradiation of model B (CN). In the present invention,
As described above, the magnetic characteristics are made variable by light irradiation. To supplement the term “spin”, the reason why the term “magnetic ion unit” is used in the present invention as described above is that ferromagnetism has ferromagnetic properties because spins are parallel (J> 0). Bring
Ferrimagnetism means that the spins are antiparallel (J <0), but because of their different sizes, magnetization is left behind by subtraction, resulting in a ferromagnet. Without two types of spins, Since the concept does not exist, the term "magnetic ion unit" is used as a combination of magnetic ions.

Further, the "antiferromagnetic material" in the present invention
The phrase does not mean in the usual sense "antiferromagnetic", that is, a state in which spins of the same type or size are antiparallel, ie, do not become magnets. In the ferro-ferri mixed magnetic material of the present invention, the term "antiferromagnetic material" is used to mean that the upward spin and the downward spin having different sizes cancel each other out to form a magnet as a whole.

It goes without saying that the molecular mixed magnetic material of the present invention whose magnetic properties can be varied by light irradiation is not particularly limited in its constituent elements and molecular species. The molecular mixed magnetic material of the present invention is constituted as a composition whose magnetic properties are variable according to the light irradiation. The configuration will be designed also as a theory of molecular magnetism. For example, if the composition is

[0014]

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And the like are exemplified. Also, the method for producing the molecular mixed magnetic material of the present invention is appropriately considered. Hereinafter, examples will be described, and the embodiments of the present invention will be described in further detail along the examples.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, Fe _1.5 Cr (CN) ₆ as a CN-bridged metal complex exhibiting a decrease in magnetization upon light induction will be described. The sample Fe _1.5 Cr (CN) ₆ is composed of FeCl ₂ and K
The ₃ Cr (CN) ₆ aqueous solution obtained by mixing. From the results of elemental analysis, composition formula _{Fe 1.5 Cr (CN) 6 ·} 7.5H
It was confirmed to be ₂ O. According to the result of X-ray powder diffraction, the structure was a face-centered cubic lattice and the lattice constant was 10,616A. The magnetic measurement was performed using SQUID.
From the magnetization vs. temperature curve, Tc is 21K and the Weiss temperature is 2
At 7K, this indicates that the complex is ferromagnetic.
The magnetization at 5T (Tessler) is 6.6 μ per formula quantity.
B. This complex is in the visible region (λ _max = 454 n
m) shows an electron transfer absorption band between metal (Fe ^II ) and metal (Cr ^III ).

[0017] When an external magnetic field was carried out a few hours light irradiation in the 5K in the _{10G, Fe 1.5 Cr (CN)} 6 · 7.5H
The magnetization of ₂ O decreased. This effect was maintained at 5K for several days. In this case, a high-pressure mercury lamp was used as a light source for examining the magneto-optical effect. Light is SQUID through optical fiber
And irradiated the sample. The powder sample was sandwiched between commercially available cellophane tapes and attached to the tip of an optical fiber.

FIG. 2 of the attached drawings shows Fe Fe before and after light irradiation.
_{1.5 Cr (CN) 6 · 7.5H} 2 O of temperature and shows the relationship between the saturation magnetization. When the sample was annealed to 70K, the magnetization returned to the value before irradiation. This indicates that the magnetization reduced by light was thermally restored to the magnetization before irradiation.

Next, an attempt was made to cause magnetic pole reversal in a CN-bridged metal complex using this system. Where F
e _{1.5 Since} Cr (CN) ₆ is a ferromagnetic material, Mn _1.5
Cr (CN) ₆ · 7.5H ₂ O (Tc = 67K) was selected for the ferri-ferri ferri mixed magnetic material. Mn _1.5
Cr (CN) ₆ .7.5H ₂ O has no absorption in the visible region, and its magnetization is not changed by light. Theoretically Fellow ferri mixed magnetic material _{(Fe x Mn 1-x)} 1.5 Cr (C
In (N) ₆ , Cr ^III and Fe ^II or Mn ^III are connected alternately, so that the parallel spin (Cr ^III ,
Fe ^II ) and antiparallel spin (Mn ^II ) cancel each other out at the mixing ratio, the saturation magnetization disappears at x = 1/3, and x = 1/1.
Complexes near 3 are expected to exhibit negative magnetization.

Based on this prediction, (Fe _x Mn _1-x )
Synthesis of _1.5 Cr (CN) ₆ was performed. Tc rises from 67K to 21K with increasing x. The saturation magnetization at 5K also changes systematically with x. x = 0 to x =
Between 0.38 the magnetization decreases and increases when x = 0.38. The vicinity of x = 0.38 is a minimum point and becomes almost zero.

FIG. 3 shows (Fe _0.4 Mn _0.6 ) _1.5 Cr
3 shows the relationship between the temperature of (CN) ₆ and the saturation magnetization. As shown in FIG. 3, the material with x = 0.40 showed negative magnetization at low temperature. When this complex was irradiated with a mercury lamp at 15K for several hours, the magnetization, which was negative at 15K, was positively reversed.

FIG. 4 shows (Fe _0.4 M) before and after light irradiation.
It shows the relationship between the temperature of n _0.6 ) _1.5 Cr (CN) ₆ and the saturation magnetization. This magnetic pole reversal is caused by the (Fe
(Cr site) was caused by a change in the ratio between the ferro portion and the ferri portion due to a decrease in magnetization. In addition, the magnetization of this material was restored by increasing the temperature to 80K.

It was confirmed that the magnetic pole inverted by light returned thermally, and that the repetition was possible. FIG.
e _0.4 Mn _0.6 ) _1.5 Cr (CN) ₆ showing the repetition of magnetic pole reversal.

[0024]

According to the present invention, as described in detail above, a molecular mixed magnetic material having excellent magnetic properties and controlled magnetic properties such as photoreversible magnetic reversal can be provided. Further, according to the present invention, it is possible to provide a photo-molecular motor applied to a micro machine, a medical material, a new photovoltaic power generation, and the like by using the magnetic pole reversal material as one embodiment.

[Brief description of the drawings]

FIG. 1 is a diagram showing magnetization temperature curves before and after light irradiation of a model of (A1 _x A2 _{1 -x} ) _1.6 B (CN) ₆ .

[Figure 2] before and after light irradiation _{Fe 1.5 Cr (CN) 6 ·} 7.5
FIG. 4 is a diagram showing a relationship between the temperature of H ₂ O and the magnetization at an external magnetic field of 10 G.

FIG. 3 is a diagram showing the relationship between the temperature of (Fe _0.4 Mn _0.6 ) _1.5 Cr (CN) ₆ and the magnetization at an external magnetic field of 10 G.

FIG. 4 (Fe _0.4 Mn _0.6 ) _1.5 Cr before and after light irradiation
FIG. 9 is a diagram showing a relationship between the temperature of (CN) ₆ and the magnetization at an external magnetic field of 10 G.

FIG. 5 is a diagram showing a state in which magnetic pole reversal of (Fe _0.4 Mn _0.6 ) _1.5 Cr (CN) ₆ is repeated.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomokazu Yata 3-12 Morinosato, Atsugi-shi, Kanagawa Bell Breeze Morinosato No.2 Building No.301

Claims (7)

[Claims] 1. A molecular magnetic material having at least one magnetic ion unit of a molecular magnetic material exhibiting ferromagnetism and at least one magnetic ion unit of a molecular magnetic material exhibiting ferrimagnetism. A molecular mixed magnetic material characterized by: 2. The molecular mixed magnetic material according to claim 1, wherein the material is a ferromagnetic material and an antiferromagnetic material. 3. The molecular mixed magnetic material according to claim 1, wherein magnetic properties such as saturation magnetization, coercive force, residual magnetization, and magnetic phase transition point are variable. 4. The molecular mixed magnetic material according to claim 1, wherein the magnetic material is a multi-component metal complex in which the magnetic ion unit is a transition metal. 5. At least as a magnetic ion, M ₁ -B-M ₂ (M ₁ , M ₂ and B are magnetic ions, and M ₁ and M ₂
Have an exchange interaction (J) with B with J> 0 and J <0 for B), respectively, and have a magnetic ion M ₁
And molecular mixing magnetic material according to claim 4 in which the abundance ratio of M ₂ is controlled. 6. The magnetic material according to claim 1, wherein the magnetic properties are variable with temperature. 7. The magnetic material according to claim 1, wherein the magnetic pole is reversible.