JP4999016B2 - Multiferroic element - Google Patents

Description

  The present invention relates to a multiferroic element as a new functional element having both ferroelectricity and ferromagnetism, and it is possible to generate a displacement current by repetitive magnetization reversal. provide. In addition, an element capable of generating electric polarization by an external magnetic field and controlling the intensity and direction thereof is provided. In addition, an element capable of controlling the intensity and direction of magnetization by an external electric field is provided. Further, it is used for a magnetic sensor necessary for reading information stored by magnetization. Furthermore, this element can also be applied to technologies related to memory elements.

  The present inventors have proposed a multiferroic element made of a multiferroic solid material having both ferroelectricity and ferromagnetism, and using a Y-type ferrite compound that generates electric polarization by an external magnetic field (see below). (See Patent Literature 1 and Non-Patent Literature 1).

International Publication No. 07/135817

S. Ishiwata et al. , Science, Vol. 319, no. 5870, pp. 1643-1647 (2008) Z. Somogyvari et al. , Journal of Magnetics and Magnetic Materials, Vol. 304, pp. e775-e777 (2006) H. Katsura et al. Phys. Rev. Lett. Vol. 95,057205 (2005)

The Y-type ferrite materials such as Ba ₂ Mg ₂ Fe ₁₂ O ₂₂ proposed above have problems such as low saturation magnetic polarization, and have not been put into practical use as permanent magnets. Therefore, if the multiferroics function can be obtained with the same or the same kind of raw material as the permanent magnet solid material that has already been put into practical use as a permanent magnet, the main starting materials are the same, and the firing conditions of the subsequent production process are also the same. It is very desirable from the viewpoint of productivity because it can be made the same condition.

  In view of the above situation, the present invention is capable of inducing current in an external magnetic field and controlling the intensity and direction of electric polarization with an external magnetic field by an M (magnetopram bite) type ferrite magnet already produced in large quantities on the market. Another object of the present invention is to provide a multiferroic element capable of controlling the intensity and direction of magnetization induced by an external electric field and operable at an operating environment temperature of room temperature.

In particular, M (magnetoprambite) type ferrite expressed as AFe ₁₂ O ₁₉ or AO 6 (Fe ₂ O ₃ ), characterized in that A is an element composed of Ba and Sr, is widely used in the world. It is a permanent magnet that has the largest production scale. In fact, the production of permanent magnets in 2004 is 690,000 tons per year, including both M-type sintered ferrite magnets and M-type ferrite bonded magnets. Even after the development of rare-earth magnets with a large magnetic susceptibility, there are several stages. However, since raw materials are inexpensive and advantageous in terms of cost, they are increasing year by year. The raw material is made of barium and iron, and the resources are extremely abundant, which is useful from the viewpoint of effective use of earth resources. Ferrite permanent magnets can be applied to motors for rotating equipment (OA, FA, home appliances, automotive, generators), control equipment (sensors, switches), application machines such as magnet rolls for copiers and laser printers, etc. A wide variety. The present invention provides a multiferroic element related to this M-type ferrite permanent magnet.

[1 ] A multiferroic element composed of a multiferroic solid material having both ferroelectricity and ferromagnetism composed of M (magnetoprambite) type ferrite, and inducing an electric current by applying an external magnetic field at room temperature. The multiferroic solid material is AFe _12-x B _x O ₁₉ M (magnetoprambite) type ferrite, and A is composed of Ca, Ba, Sr, Pb or a mixture of these two elements, and B Is a trivalent element, and the range of x is 1.6 <x ≦ 2 .

[ 2 ] A multiferroic element made of a multiferroic solid material having both ferroelectricity and ferromagnetism composed of M (magnetoprambite) type ferrite and inducing an electric current by applying an external magnetic field at room temperature. The multiferroic solid material is AFe _12-xy B _x C _y O ₁₉ M (magnetoprambite) type ferrite, and A is composed of Ca, Ba, Sr, Pb or a mixture of these two elements. , B is Sc which is a trivalent element, C is made of Mg, Ca, Zn, Co, Ni, Cu or a mixture of these two elements which are divalent elements, and the range of x is 1.6 < The range of x ≦ 2 and y is 0 <y ≦ 1 .

[ 3 ] A multiferroic element composed of a multiferroic solid material having both ferroelectricity and ferromagnetism composed of M (magnetoprambite) type ferrite and inducing an electric current by applying an external magnetic field at room temperature. The multiferroic solid material is a single crystal produced by a floating melting zone manufacturing method using a light lamp in a high-pressure gas atmosphere of 2 atmospheres or more in an oxygen gas atmosphere .

[ 4 ] A multiferroic solid material consisting of M (magnetoprambite) type ferrite, which combines ferroelectricity and ferromagnetism, and can control the intensity and direction of electric polarization by applying an external magnetic field at room temperature. A multiferroic element, wherein the multiferroic solid material is AFe _12-x B _x O ₁₉ M (magnetoprambite) type ferrite, and A is Ca, Ba, Sr, Pb or two of these It is composed of a mixture of elements, B is Sc which is a trivalent element, and the range of x is 1.6 <x ≦ 2 .

[ 5 ] Made of M (ferroplumbite) type ferrite, which is a multiferroic solid material that combines ferroelectricity and ferromagnetism, and can control the intensity and direction of electric polarization by applying an external magnetic field at room temperature. In the multiferroic element, the multiferroic solid material is M (magnetoprambite) ferrite of AFe _12-xy B _x C _y O ₁₉ , and A is Ca, Ba, Sr, Pb, or two of these. It is composed of a mixture of two kinds of elements, B is Sc which is a trivalent element, C is composed of Mg, Ca, Zn, Co, Ni, Cu which are divalent elements or a mixture of these two kinds of elements, and x The range is 1.6 <x ≦ 2, and the range y is 0 <y ≦ 1 .

[ 6 ] Made of M (ferroplumbite) type ferrite, which is a multiferroic solid material that combines ferroelectricity and ferromagnetism, making it possible to control the strength and direction of electric polarization by applying an external magnetic field at room temperature. In the multiferroic element, the multiferroic solid material is a single crystal produced by a floating melting zone manufacturing method using a light lamp in a high-pressure gas atmosphere of 2 atmospheres or more in an oxygen gas atmosphere .

[ 7 ] A multiferroic solid material consisting of M (magnetoprambite) type ferrite that has both ferroelectricity and ferromagnetism, and can control the strength and direction of magnetization by applying an external electric field at room temperature. It is a ferroic element, and the multiferroic solid material is AFe _12-x B _x O ₁₉ M (magnetoprambite) type ferrite, and A is Ca, Ba, Sr, Pb or these two kinds of elements. B is Sc which is a trivalent element, and the range of x is 1.6 <x ≦ 2 .

[ 8 ] A multiferroic solid material composed of M (magnetoprambite) type ferrite that has both ferroelectricity and ferromagnetism, and can control the strength and direction of magnetization by applying an external electric field at room temperature. In the ferroic element, the multiferroic solid material is AFe _12-xy B _x C _y O ₁₉ M (magnetoprambite) type ferrite, and A is Ca, Ba, Sr, Pb, or two kinds thereof. B is a trivalent element Sc, C is a divalent element Mg, Ca, Zn, Co, Ni, Cu or a mixture of these two elements, and x The range is 1.6 <x ≦ 2, and the range y is 0 <y ≦ 1 .

[ 9 ] A multiferroic solid material composed of M (magnetoprambite) type ferrite that has both ferroelectricity and ferromagnetism, and can control the strength and direction of magnetization by applying an external electric field at room temperature. In the ferroic element, the multiferroic solid material is a single crystal produced by a floating melting zone manufacturing method using a light lamp in a high-pressure gas atmosphere having an oxygen gas atmosphere of 2 atm or more .

According to the present invention, the following effects can be achieved.
(1) Since the displacement current continues to flow through the wiring by repetitive alternating magnetic field (magnetic field reversal), it functions as a nanometer-sized generator. For example, by applying a repetitive magnetic field from outside the human body, driving power can be applied to a micro motor in a blood vessel of the human body.
(2) Since the magnetic sensor part and the electric polarization generating part can be made of the same solid material, it can be used as a data reading magnetic sensor that functions without having a special shape. As a result, the structure of the magnetic sensor element is simplified, resulting in significant cost merit. Since this magnetic sensor element can be miniaturized to a nanometer size, it becomes a magnetic sensor that can cope with the miniaturization of the magnetized region for storing information.

  (3) Unlike the magnetic memory element (MRAM) using a current-induced magnetic field generation mechanism, the multiferroic memory element is an electric field induced, and thus a memory element that has a small current flow and can significantly reduce power consumption. Since the induced magnetization has hysteresis, it has a memory effect and becomes a nonvolatile memory element. Since the device structure is also simple, a nanometer-sized fine memory structure can be formed, and a high-density memory device is possible. Fewer layer configurations dramatically reduce process costs. A new multiferroic nonvolatile memory device with low power consumption, high integration, and low manufacturing cost becomes possible.

It is a schematic diagram of the multiferroic nanogenerator as a multiferroic element which shows 1st Example of this invention. It is a schematic diagram of the multiferroic magnetic sensor element which shows 2nd Example of this invention. FIG. 3 is a layout diagram of multiferroic memory cells according to the present invention. It is an experiment arrangement | positioning figure which shows the confirmation experiment of the magnetic field induced current generation | occurrence | production of the multiferroic element concerning this invention. FIG. ₅ is a diagram showing the correlation between the crystal orientation of the multiferroic solid material BaFe _10.2 Sc _1.75 Mg _{0.05 A 19} used in the experimental arrangement in FIG. 4 and an external magnetic field. It is a diagram illustrating an external magnetic field dependence of the multiferroic solid which is a material BaFe _10.2 Sc _1.75 Mg _0.05 O ₁₉ electric polarization that occur when applying an external magnetic field to the crystal material of the present invention. The correlation between the crystal orientation of the hexagonal structure of the multiferroic solid material used in Fig. 6, the external magnetic field and the direction of polarization generated (double circles are perpendicular to the page and indicate the direction from the front to the back). FIG. In BaFe _10.35 Sc _1.6 Mg _0.05 O ₁₉ is a multiferroic solid material of the present invention, is a diagram showing a current (a) an electric polarization (b) that occurs when applying an alternating external magnetic field (c). It is a diagram showing the crystal structure and magnetic structure of the M-type ferrite BaFe ₁₂ O _19. It is a conical spiral spin structure diagram below Tc of BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal material which is a multiferroic solid material according to the present invention. The BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal material, which is a multiferroic solid material according to the present invention, is perpendicular to the c-axis direction when the Sc concentration x is 1.6 to 2. It is a figure which shows the temperature dependence of magnetization of a [100] direction. In multiferroic _{BaFe 12-x-δ Sc x} Mg δ O 19 (δ = 0.05) is a hex solid material crystalline material of the present invention, transition temperature showing a conical helical spin structure (Tc) Sc concentration x It is a figure which shows the relationship. [001] direction (c-axis) when the Sc concentration x is 1.75 in the BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal material which is a multiferroic solid material according to the present invention. ) And the temperature dependence of magnetization in the [100] direction perpendicular thereto. Displacement current generated by magnetic field induction when the Sc concentration x is 1.75 in the BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal material which is a multiferroic solid material according to the present invention. It is a figure which shows the temperature dependence of. A single crystal of BaFe _10.2 Sc _1.75 Mg _0.05 O ₁₉ is a multiferroic solid material according to the present invention is a photograph alternative to a drawing showing.

A multiferroic nanogenerator as a multiferroic element has a structure made of a multiferroic solid material sandwiched between metal electrodes, is arranged so as to apply an alternating magnetic field in parallel to the electrodes, and flows between the electrodes. Use current.
A multiferroic magnetic sensor element has a structure made of a multiferroic solid material sandwiched between metal electrodes, and is generated in a direction substantially perpendicular to the magnetic field generated by a leakage magnetic field of magnetization corresponding to information. What is necessary is just to set it as the structure which detects an electric polarization with a voltmeter.

  The multiferroic memory device is made of a multiferroic solid material sandwiched between two metal electrodes, and is selected by applying a voltage between a specific selected bit line and a word line. Magnetization in a specific direction is generated in a single memory element sandwiched between lines. The generated magnetization has a memory function. A non-magnetic solid material is embedded between the memory elements. For data reading, 0 or 1 may be determined based on the voltage intensity caused by the electric polarization generated between a specific selected bit line and word line.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a schematic diagram of a multiferroic nanogenerator as a multiferroic element showing a first embodiment of the present invention.
In this figure, 1 is a multiferroic solid material, 2 is a metal electrode formed on both sides of the multiferroic solid material 1, 3 is a wiring connected to the metal electrode 2, and 4 is connected to the wiring 3. An electrical device 5 is an alternating magnetic field that acts on the multiferroic solid material 1.

  As shown in FIG. 1, the multiferroic nano-generator has a structure made of a multiferroic solid material 1 sandwiched between metal electrodes 2 and is arranged so as to apply an alternating magnetic field 5 in parallel to the metal electrodes 2. The current flowing between the metal electrodes 2 may be used for the operation of the electric device 4. According to this embodiment, since the displacement current 6 continues to flow in the wiring 3 due to repetitive alternating magnetic field (magnetic field reversal) 5, it functions as a nano-sized generator in which a nanometer-sized power generation coil is incorporated. For example, by applying a repetitive magnetic field from the outside of the human body, driving power can be applied to a micro-sized micromotor in a blood vessel of the human body.

FIG. 2 is a schematic view of a multiferroic magnetic sensor element showing a second embodiment of the present invention.
In this figure, 11 is a multiferroic solid material, 12 is a metal electrode formed on both sides of the multiferroic solid material 11, 13 is a wiring connected to the metal electrode 12, and 14 is connected to the wiring 13. A voltmeter 15 is a perpendicular magnetic recording material in which data acting on the multiferroic solid material 11 is stored.

As shown in FIG. 2, the multiferroic magnetic sensor element has a structure made of a multiferroic solid material 11 sandwiched between metal electrodes 12, and has a leakage magnetic field of magnetization corresponding to information of the perpendicular magnetic recording material 15. What is necessary is just to make it the structure which measures the electric polarization which generate | occur | produced in the direction substantially perpendicular | vertical to the magnetic field with the voltmeter 14 with the generated magnetic field.
According to this embodiment, the multiferroic magnetic sensor element can generate electric polarization by a magnetic field from the perpendicular magnetic recording material 15 in which data is stored, and thus functions as a magnetic sensor for reading data.

  In this case, since the magnetic sensor part and the electric polarization generating part can be made of the same solid material, it functions as a magnetic sensor without having a special shape. As a result, the structure of the magnetic sensor element is simplified, resulting in significant cost merit. In addition, since the magnetic sensor element can be miniaturized to a nanometer size, the magnetic sensor element can sufficiently cope with the progress of the miniaturization of the magnetization region for storing information.

FIG. 3 is a layout view of multiferroic memory cells according to the present invention.
In this figure, 21 is a multiferroic solid material, 22 is a metal electrode formed above and below the multiferroic solid material 21, 23 is a multiferroic memory cell, 24 is a bit line, and 25 is a word line.
As shown in FIG. 3, the multiferroic memory element is composed of multiferroic memory cells 23 arranged in a plane and made of a multiferroic solid material 21 sandwiched between two metal electrodes 22. By applying a voltage between a specific selected bit line 24 and a word line 25 from a DC power supply or an AC power supply via a wiring, a multiferro that is sandwiched between the selected bit line 24 and the word line 25 is applied. A magnetization in a specific direction is generated in the X memory cell 23. The generated magnetization has a memory function. A non-magnetic solid material is embedded between the memory elements. On the other hand, for data reading, 0 or 1 is determined based on the voltage intensity caused by the electric polarization generated between a specific selected bit line 24 and word line 25.

FIG. 4 is an experimental layout showing a confirmation experiment of magnetic field induced current generation of the multiferroic element according to the present invention.
In this figure, 31 is a multiferroic solid material, 32 is a metal electrode formed vertically so as to sandwich the multiferroic solid material 31, 33 is the direction of the magnetic field applied from the outside, and 34 is the generated electric polarization. Direction. Reference numeral 35 denotes an ammeter for measuring a current between the upper and lower metal electrodes 32 of the multiferroic solid material 31 generated by the induced electric polarization. A silver paste is used as the electrode material, but there is no problem even if it is a metal such as aluminum, gold, or platinum.

FIG. 5 is a diagram showing the correlation between crystal orientation, external magnetic field, and electrode arrangement when BaFe _10.2 Sc _1.75 Mg _0.05 O ₁₉ is used as the multiferroic solid material 31 in FIG. As is clear from this figure, the direction of the external magnetic field is 45 ° from the crystal axis [100] of the hexagonal structure of BaFe _10.2 Sc _1.75 Mg _0.05 O ₁₉ (δ = 0.05), and the generated electric polarization Is the [120] direction.

FIG. 6 is a diagram showing the external magnetic field dependence of the electric polarization generated when an external magnetic field is applied to the BaFe _10.2 Sc _1.75 Mg _0.05 O ₁₉ crystal material which is the multiferroic solid material of the present invention.
FIG. 7 shows the crystal orientation of the hexagonal structure of the multiferroic solid material used in FIG. 6, the external magnetic field, and the direction of the generated polarization (the double circle indicates the direction perpendicular to the page and from the front to the back of the page). It is a figure which shows correlation.

  As shown in these figures, a magnetic field of 10K Oersted is applied in advance from the [100] direction to the [001] direction at an angle of 45 degrees, and an electric field of about several hundred volts / cm is applied in the [120] direction (polling). . Thereafter, when an external magnetic field is applied again from zero to plus at an angle of 45 degrees from the [100] direction to the [001] direction, the electric polarization (solid line) in the [120] direction changes to the plus direction. When the poling conditions are the same magnetic field direction as described above and a negative electric field is applied in the [120] direction, the generated electric polarization is reversed (broken line). The measurement temperature is -263 ° C.

FIG. 8 is a diagram showing current (a) and electric polarization (b) generated when an AC external magnetic field (c) is applied in BaFe _10.35 Sc _1.6 Mg _0.05 O ₁₉ which is a multiferroic solid material of the present invention. 8A shows displacement current (pA / mm ² ) with respect to elapsed time (sec), FIG. 8B shows electric polarization (μC / m ² ) with respect to elapsed time (sec), and FIG. The alternating magnetic field (kOe) with respect to the elapsed time (sec) is shown.

When an alternating magnetic field that vibrates positively and negatively is applied to the BaFe _10.35 Sc _1.6 Mg _0.05 O ₁₉ crystal material [FIG. 8 (c)], positive and negative displacement currents flow in accordance with the alternating magnetic field [FIG. 8 (a)], and It can be seen that the electric polarization alternately occurs in positive and negative [FIG. 8 (b)]. This result shows that an alternating current and an alternating potential are generated by alternating magnetization.
FIG. 9 is a diagram showing the crystal structure and magnetic structure of M-type ferrite BaFe ₁₂ O ₁₉ (the direction of spin is indicated by an arrow). The crystal structure is a hexagonal crystal structure. As shown in the figure, the R block of the hcp structure of the sequence ABAB... And the S block of the fcc structure of ABCABC... Share the c axis to form one molecule, and R ^* S rotated 180 degrees with respect to this axis. ^* Combined with a block, two molecules form one unit cell. 6 upward spins across S and R (a), 2 downward spins in R block (b), 1 upward spin in S block (c), 2 downward spins in S block (d) in one upward spin R block (e), the magnetic moment per molecule becomes _{(8-4) * 5μ B = 20μ} B. Its magnetic structure is a ferri-type spin structure having an easy axis of magnetization in the [001] direction. The main reason why these M-type ferrites are excellent permanent magnet materials is the presence of large uniaxial crystal anisotropy energy with the c-axis direction as the easy magnetization direction. It is ferrimagnetic (a type of ferromagnetism) at room temperature.

As shown in FIG. 10, the magnetic structure of the BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal doped with Sc is different from the magnetic structure of BaFe ₁₂ O ₁₉ at a low temperature. Type spiral spin structure.
FIG. 11 shows the c-axis when the Sc concentration x is 1.6 to 2 in a BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal material which is a multiferroic solid material according to the present invention. The temperature dependence of magnetization in the [100] direction perpendicular to the direction is shown. The magnetization in the [100] direction has a maximum value (Tc). When the Sc concentration is 0, the magnetization is in the c-axis direction, and the magnetization in the [100] direction has no value (small). When Sc trivalent ions having no spin are introduced into the iron site, the strong spin anisotropy in the c-axis direction is weakened. As a result, the spin has a component in the ab plane direction. That is, the magnetization in the [100] direction is increased. At a temperature equal to or lower than the temperature at which the magnetization has the maximum value (Tc), a spin-rotation structure of the spin as shown in FIG. 12 starts with the inclined spin correlated with the adjacent iron site in the c-axis direction. The temperature range from the temperature (Tc) showing the maximum value of the magnetization to the low temperature is the temperature range showing the conical spiral spin structure. This has been confirmed from Mossbauer experiments (see Non-Patent Document 2 above). In the case of such a conical spiral spin structure, when an external magnetic field is applied in a direction shifted from the [001] direction into the plane of the paper, it is predicted that an electric polarization is generated perpendicular to the plane of the paper (the above non-existence). (See Patent Document 3). That is, in this temperature range, a multiferroic state in which a ferroelectric phase induced by a conical spiral spin structure and a ferromagnetic phase (a ferri having a conical spiral spin structure) coexist is obtained.

FIG. 12 shows the transition temperature (Tc) and Sc showing a conical helical spin structure in a BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal material which is a multiferroic solid material according to the present invention. It is a figure which shows the relationship with the density | concentration x. It can be seen that when the Tc is in the range of room temperature (300K) or more, the Sc concentration is 1.6 or more and less than 2.
FIG. 13 shows the c-axis when the Sc concentration x is 1.75 in the BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal material, which is a multiferroic solid material according to the present invention. It is a figure which shows the temperature dependence of the magnetization of a [100] direction perpendicular | vertical to a] direction and a c-axis. It shows that the maximum value Tc of the magnetization curve in the [100] direction is a temperature of 370 K (97 ° C.) above room temperature.

FIG. 14 shows the generation of magnetic field induction when the Sc concentration x is 1.75 in the BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal material, which is a multiferroic solid material according to the present invention. FIG. It shows that the displacement current rises from a temperature around 370 K (97 ° C.), and that a magnetization-induced current is generated below this temperature (Tc). That is, the multiferroics characteristic is shown in this temperature region. Tc shows a high temperature of about 97 ° C. above room temperature because the BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal material stably uses multiferroic properties at room temperature. It shows a very important characteristic for practical use. In addition, this is the first example in the world showing that this latest multiferroic function can be applied at practical temperatures.

Here, the reason why 0.05 Mg is doped is to prevent a reduction in electrical resistance due to mixing of a small amount of iron divalent ions during preparation of a small amount of sample. If it is a divalent ion, the same effect can be expected, and a divalent ion of Ca, Zn, Co, Ni, or Cu may be used.
In addition, as shown in claims 1, 4 and 7 , the multiferroic solid material is AFe _12-x B _x O ₁₉ M (magnetoprambite) type ferrite, and A is Ca, Ba, Sr, Pb or It consists of a mixture of these two elements, B is Sc which is a trivalent element, and the range of x is 1.6 <x ≦ 2.

Further, as shown in claims 2, 5 , and 8 , the multiferroic solid material is AFe _12-xy B _x C _y O ₁₉ M (magnetoprambite) type ferrite, and A is Ca, Ba, Sr, Pb or a mixture of these two elements, B is a trivalent element Sc, C is a divalent element Mg, Ca, Zn, Co, Ni, Cu or these two elements. It consists of a mixture, and the range of x is 1.6 <x ≦ 2, and the range of y is 0 <y ≦ 1.

Thus, in the case of a BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal having a multiferroic material M-type ferrite structure, its current and electric polarization are generated by an external magnetic field, It was demonstrated for the first time that the polarization intensity can be stably controlled at room temperature, which is a practical temperature. The applied magnetic field strength was about 4000 Gauss in this example. Furthermore, if a material is selected, it can be induced by a weak magnetic field, and the current density can be further improved.

FIG. 15 is a drawing-substituting photograph showing a single crystal of BaFe _10.2 Sc _1.75 Mg _0.05 O ₁₉ which is a multiferroic solid material according to the present invention.
BaFe _10.2 Sc _1.75 Mg _0.05 O ₁₉ is a single crystal produced by a floating melting zone manufacturing method using a light source such as a halogen lamp in an atmosphere under a high-pressure gas. When the gas species to be applied is oxygen gas, a single-phase hexagonal crystal structure can be obtained if the pressure is 2 atm or higher.

As described above, a multiferroic solid material BaFe _12-x-δ Sc _x Mg _δ O ₁₉ (δ = 0.05) crystal having both ferroelectricity and ferromagnetism, and an electric current or electricity by an external magnetic field. Since the embodiment shows that the polarization can be controlled, it can be seen that the electric field can be formed by the electric field which is the reverse process, and the magnetization can be generated. In a ferroelectric, the positive and negative directions of electric polarization can be controlled by an electric field. If reversal of electric polarization occurs at this time, it is obvious that reversal of magnetization occurs simultaneously in a multiferroic material having a helical spin structure.

  In addition, this invention is not limited to the said Example, Based on the meaning of this invention, a various deformation | transformation is possible and these are not excluded from the scope of the present invention.

  The multiferroic element of the present invention can provide a nano-sized power generation device, a magnetic sensor that reads information on an element stored by magnetization, and a low-cost memory element.

1,11,21,31 Multiferroic solid material 2,12,22,32 Metal electrode 3,13 Wiring 4 Electrical equipment 5 AC magnetic field 6 Displacement current 14 Voltmeter 15 Perpendicular magnetic recording material 23 Multiferroic memory cell 24 bit Line 25 Word line 33 Direction of magnetic field applied from outside 34 Direction of generated electric polarization 35 Ammeter

Claims (9)

A multiferroic element made of a multiferroic solid material having both ferroelectricity and ferromagnetism composed of M (magnetoprambite) type ferrite and inducing an electric current by applying an external magnetic field at room temperature. Ferroix solid material is AFe _12-x B _x O ₁₉ M (magnetoprambite) type ferrite, A is made of Ca, Ba, Sr, Pb or a mixture of these two elements, and B is trivalent. A multiferroic element, wherein the element is Sc and the range of x is 1.6 <x ≦ 2 . A multiferroic element made of a multiferroic solid material having both ferroelectricity and ferromagnetism composed of M (magnetoprambite) type ferrite and inducing an electric current by applying an external magnetic field at room temperature. Ferroix solid material is AFe _12-xy B _x C _y O ₁₉ M (magnetoprambite) type ferrite, A is made of Ca, Ba, Sr, Pb or a mixture of these two elements, B is Sc is a trivalent element, and C is a divalent element Mg, Ca, Zn, Co, Ni, Cu or a mixture of these two elements, and the range of x is 1.6 <x ≦ 2. , Y is in a range of 0 <y ≦ 1 . A multiferroic element made of a multiferroic solid material having both ferroelectricity and ferromagnetism composed of M (magnetoprambite) type ferrite and inducing an electric current by applying an external magnetic field at room temperature. The multiferroic element, wherein the ferroic solid material is a single crystal produced by a floating melting zone manufacturing method using a light lamp in a high-pressure gas atmosphere of 2 atmospheres or more in an oxygen gas atmosphere . Multiferroics made of M (ferroplumbite) type ferrite, which is a multiferroic solid material that combines ferroelectricity and ferromagnetism, and can control the intensity and direction of electric polarization by applying an external magnetic field at room temperature A multiferroic solid material is AFe _12-x B _x O ₁₉ M (magnetoprambite) type ferrite, and A is Ca, Ba, Sr, Pb or a mixture of these two elements. A multiferroic element characterized in that B is Sc, a trivalent element, and the range of x is 1.6 <x ≦ 2 . Multiferroics made of M (ferroplumbite) type ferrite, which is a multiferroic solid material that combines ferroelectricity and ferromagnetism, and can control the intensity and direction of electric polarization by applying an external magnetic field at room temperature The multiferroic solid material is an AFe _12-xy B _x C _y O ₁₉ M (magnetoprambite) type ferrite, and A is Ca, Ba, Sr, Pb or these two kinds of elements B is Sc which is a trivalent element, C is Mg, Ca, Zn, Co, Ni, Cu or a mixture of these two elements which are divalent elements, and the range of x is 1.6 <x ≦ 2, and the range of y is 0 <y ≦ 1 . Multiferroics made of M (ferroplumbite) type ferrite, which is a multiferroic solid material that combines ferroelectricity and ferromagnetism, and can control the intensity and direction of electric polarization by applying an external magnetic field at room temperature A multiferroic element, wherein the multiferroic solid material is a single crystal produced by a floating melting zone manufacturing method using a light lamp in a high-pressure gas atmosphere of 2 atmospheres or more in an oxygen gas atmosphere . A multiferroic element made of multiferroic solid material consisting of M (magnetoprambite) type ferrite, which has both ferroelectricity and ferromagnetism, and can control the strength and direction of magnetization by applying an external electric field at room temperature The multiferroic solid material is AFe _12-x B _x O ₁₉ M (Magnet Plumbite ) type ferrite, and A is Ca, Ba, Sr, Pb or a mixture of these two elements. B is Sc which is a trivalent element, and the range of x is 1.6 <x ≦ 2 . A multiferroic element made of multiferroic solid material consisting of M (magnetoprambite) type ferrite, which has both ferroelectricity and ferromagnetism, and can control the strength and direction of magnetization by applying an external electric field at room temperature The multiferroic solid material is M (magnetoprambite) type ferrite of AFe _12-xy B _x C _y O ₁₉ , and A is Ca, Ba, Sr, Pb or these two elements. It is composed of a mixture, B is Sc which is a trivalent element, C is composed of Mg, Ca, Zn, Co, Ni, Cu which are divalent elements or a mixture of these two elements, and the range of x is 1 .Multidot.6 <x.ltoreq.2, y is in the range of 0 < y.ltoreq.1. A multiferroic element made of multiferroic solid material consisting of M (magnetoprambite) type ferrite, which has both ferroelectricity and ferromagnetism, and can control the strength and direction of magnetization by applying an external electric field at room temperature The multiferroic solid material is a single crystal produced by a floating melting zone manufacturing method using a light lamp in a high pressure gas atmosphere of 2 atmospheres or more of oxygen gas atmosphere .