Magneto-optical material and method for manufacturing the same

Abstract

The present invention provides a magneto-optical material having a nanogranular structure that can reduce the effects of a demagnetizing field. [Solution] The magneto-optical material 10 of the present invention has a nanogranular structure in which nanoparticles 12 are dispersed in a matrix 11. The matrix 11 is a fluoride, oxide, or nitride matrix containing at least one element selected from the group consisting of Li, Be, Mg, Al, Si, Ca, Sr, Ba, Bi, Ti, rare earth elements, Zr, Nb, Hf, and Ta. The nanoparticles 12 are magnetic nanoparticles containing at least one metal having magnetization selected from the group consisting of particles of at least one metal or alloy of Fe, Co, and Ni. Furthermore, there is a density variation in the distribution of nanoparticles 12 present in the matrix 11 in a specified direction.

Description

Technical Field

[0001] The present invention relates to a magneto-optical material and a method for manufacturing the magneto-optical material.

Background Art

[0002] In order to increase the Faraday rotation angle of a layer having a magneto-optical effect, the applicant of the present application has proposed a magneto-optical material having a nanogranular structure in which metal particles of nanometer size are dispersed in an insulator matrix (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] It is known that a magnetic material has a demagnetizing field H' (coercive force). Due to the presence of the demagnetizing field H', the internal magnetic field H of the magneto-optical material decreases compared to the external magnetic field H0 (see the following formula (1)).

[0005] H = H0 - H' ··· (1)

[0006] In the existing magneto-optical material having a nanogranular structure disclosed in Patent Document 1, due to the demagnetizing field H' of the entire magnetic material, there is a problem that the internal magnetic field becomes small and the Faraday rotation angle decreases.

[0007] The present invention solves such problems. Specifically, an object of the present invention is to provide a magneto-optical material having a nanogranular structure capable of reducing the influence of the demagnetizing field H'.

Means for Solving the Problems

[0008] To achieve the above objective, the magneto-optical material of the present invention and the method for manufacturing the magneto-optical material are characterized by having the following inventive features.

[0009] The magneto-optical material of the present invention is a magneto-optical material having a nanogranular structure in which nanoparticles are dispersed in a matrix, The matrix is ​​a fluoride, oxide, or nitride matrix containing at least one element selected from the group consisting of Li, Be, Mg, Al, Si, Ca, Sr, Ba, Bi, Ti, rare earth elements, Zr, Nb, Hf, and Ta. The nanoparticles are magnetic nanoparticles comprising a metal having at least one magnetization selected from the group consisting of particles of at least one metal or alloy selected from Fe, Co, and Ni, The distribution of the nanoparticles present in the matrix varies in density in a given direction.

[0010] In any of the magneto-optical materials described above, It is preferable that the second density, which is the density of nanoparticles located near the center of the magneto-optical material, is higher or lower than the first density, which is the density of nanoparticles located near the outer surface of the magneto-optical material.

[0011] In any of the magneto-optical materials described above, It is preferable that the ratio of the second density to the first density (second density / first density) is 1.14 or greater, or 0.88 or less.

[0012] In any of the magneto-optical materials described above, It is preferable that the density of the nanoparticles gradually decreases or increases in a specified direction.

[0013] The present invention's method for manufacturing magneto-optical materials is as follows: A method for manufacturing a magneto-optical material as described above, A step of manufacturing a nanogranular material having a nanogranular structure, in which the nanoparticles dispersed in the matrix are adjusted to a specified density by controlling the amount of power supplied to the first target constituting the nanoparticles and the amount of power supplied to the second target constituting the matrix, respectively.

[0014] In an aggregate of nanoparticles such as a nanogranular structure, its magnetization process changes due to changes in the magnetic interaction between the nanoparticles. According to the magneto-optical material as described above and the magneto-optical material manufactured by the manufacturing method as described above, the density of the nanoparticles is adjusted, and the distance between the nanoparticles is adjusted throughout the film. Therefore, the magnetic interaction changes to change the magnetization process of the entire film, and the demagnetizing field can be adjusted by the interaction between the densities of the nanoparticles. Specifically, a large magnetization occurs in the entire magneto-optical material, so that the demagnetizing field of the entire magneto-optical material is suppressed, and the internal magnetic field of the entire magneto-optical material is increased. Therefore, according to the magneto-optical material of the present invention and the magneto-optical material manufactured by the manufacturing method of the present invention, an increase in the Faraday rotation angle can be further achieved, and thus the sensitivity of the magneto-optical material can be improved.

Brief Description of Drawings

[0015] [Figure 1] Schematic explanatory diagram regarding the structure of the first embodiment of the magneto-optical material according to the present invention. [Figure 2] Schematic explanatory diagram regarding the structure of the second embodiment of the magneto-optical material according to the present invention. [Figure 3] Schematic explanatory diagram regarding the manufacturing method of the magneto-optical material according to the present invention. [Figure 4] Diagram showing the time-series change of the sputtering power ratio in the manufacturing process of the magneto-optical materials according to Examples 1 to 5 of the present invention. [Figure 5] Diagram showing the time-series change of the sputtering power ratio in the manufacturing process of the magneto-optical materials according to Examples 6 to 11 of the present invention. [Figure 6] Diagram showing the Faraday rotation angle according to the magnetic field of the magneto-optical materials according to Example 5, Example 8, and Comparative Example 1.

Embodiments for Carrying out the Invention

[0016] Next, embodiments of the magneto - optical material of the present invention will be described with reference to the drawings.

[0017] (Configuration) FIG. 1 and FIG. 2 are schematic explanatory diagrams regarding the structure of a magneto - optical material 10 according to an embodiment of the present invention. As shown in FIGS. 1 and 2, the magneto - optical material 10 has a nanogranular structure in which nanoparticles 12 are dispersed in a matrix 11.

[0018] In the magneto - optical material 10 as one embodiment, the matrix 11 is a fluoride, oxide or nitride matrix containing at least one or more elements selected from the group consisting of Li, Be, Mg, Al, Si, Ca, Sr, Ba, Bi and rare earth elements, and preferably is barium fluoride.

[0019] The nanoparticles 12 are magnetic nanoparticles containing at least one magnetized metal selected from the group consisting of particles of at least one metal selected from Fe, Co and Ni or an alloy thereof, and preferably are an alloy containing Fe and Co, etc. By configuring the nanoparticles from ferromagnetic metals having a large magnetization or alloys thereof, the Faraday effect due to their magnetic properties is manifested. The particle size of the nanoparticles 12 is, for example, included in the range of 2 - 20 nm. At this time, when the particle size of the nanoparticles 12 is smaller than 2 nm, the ferromagnetic property of the nanoparticles 12 is lost and the Faraday effect is not manifested. When the particle size of the nanoparticles 12 is larger than 20 nm, the light transmittance deteriorates due to the metallic properties of the nanoparticles 12. The configurations of the matrix 11 and the nanoparticles 12 are the same in the magneto - optical material 10 in other embodiments.

[0020] From the viewpoint of improving the Faraday rotation angle while ensuring light transmittance, the magneto - optical material 10 has an average composition formula Fe , ,

[0020] ,

[0019] , , Co b Ni c M w Nx O y F z It is expressed as such, where the average composition ratios a, b, c, w, x, y, z are atomic ratios, and 0≦a≦0.30, 0≦b≦0.30, 0≦c≦0.30, 0.10≦a+b+c≦0.40, 0.10≦w≦0.30, 0≦x≦0.70, 0≦y≦0.70, 0≦z≦0.70, 0.40≦x+y+z≦0.70, and a+b+c+w+x+y+z=1. The M component may be at least one element selected from the group consisting of Li, Be, Mg, Al, Si, Ca, Sr, Ba, Bi, Ti, rare earth elements, Zr, Nb, Hf, and Ta.

[0021] In the magneto-optical material 10, if there is a region where a+b+c exceeds 0.40, the light transmittance deteriorates due to the presence of such a region. Therefore, it is preferable that there is no region in the magneto-optical material 10 where a+b+c exceeds 0.40. In addition, if a+b+c is less than 0.10, the Faraday rotation angle does not occur. Therefore, it is preferable that there is at least a region in the magneto-optical material 10 where a+b+c is 0.10 or greater. In the average composition formula of the magneto-optical material 10, if a, b, c, w, x, y, and z are within the aforementioned numerical ranges and there is no region where a+b+c exceeds 0.40, then there is at least a region where a+b+c is 0.10 or greater. Thus, the magneto-optical material 10 can improve the Faraday rotation angle while ensuring light transmittance. Therefore, it is preferable that in the average composition formula of the magneto-optical material 10, a, b, c, w, x, y, and z are within the aforementioned numerical ranges, and there is no region where a+b+c exceeds 0.40.

[0022] The magneto-optical material 10 has density variations in the distribution of nanoparticles 12 present in the matrix 11 in a specified direction. The density variations can take the form of monotonically changing density, such as an increasing or decreasing function, or periodically changing density, such as a trigonometric function, in a specified direction. The specified direction is not limited to one axis direction in Cartesian coordinates, but may also be one direction in polar coordinates. Furthermore, as will be described later, the specified direction is preferably the direction of light transmission (propagation) when the magneto-optical material 10 is used in a magneto-optical element. The magneto-optical material 10 may have density variations in one specified direction, or in two or three specified directions. The change in density may be continuous or discontinuous in the specified direction.

[0023] The magneto-optical material 10 may be configured such that, for example, the density of nanoparticles 12 near the outer surface of the magneto-optical material 10 varies with respect to the second density of nanoparticles 12 near the center of the magneto-optical material 10. Here, the vicinity of the outer surface may be defined as extending from the outer surface to a point a specified distance away in a specified direction. The vicinity of the center may be defined as extending from a predetermined point to a point a specified distance away in a specified direction. The specified distance may be determined based on the length of the magneto-optical material 10 in a specified direction. For example, if the length of the magneto-optical material 10 in a specified direction (e.g., the thickness direction) is defined as d, the vicinity of the outer surface in that specified direction may be defined as the range at a distance of α × d (where α is a positive real number less than 0.5, e.g., 0.1) in the specified direction from one outer surface perpendicular to the specified direction or another outer surface opposite to one outer surface. Furthermore, the neighborhood of the center can be defined as the range of distances β×d (where β is a positive real number less than 1, e.g., 0.1) from the midpoint between one outer surface and the other towards the first outer surface in a specified direction, from the midpoint between the two outer surfaces, from the midpoint between the two outer surfaces, from the other outer surface in a specified direction, from the midpoint between the two outer surfaces, from the midpoint between the two outer surfaces, from the midpoint between the two outer surfaces, from the midpoint between the two outer surfaces, from the midpoint between the two outer surfaces, from the midpoint between the two outer surfaces, from the midpoint, from the first outer surface, from the midpoint, from the midpoint, from the first outer surface, from the midpoint, from the midpoint, from the midpoint, from the midpoint, to the other outer surface, from the distance β×d. α and β may be the same or different. Also, the range of the neighborhood of the outer surfaces may overlap with the range of the neighborhood of the center. The neighborhood of the outer surfaces and the neighborhood of the center may be adjacent to each other or they may not be adjacent.

[0024] Here, the vicinity of the outer surface and the vicinity of the center may be defined based on a density statistic in a specified direction from the outer surface. For example, if the second density is higher than the first density, the discrete or continuous distribution of density in the specified direction of the magneto-optical material 10 can be calculated, and the region where the density is less than or equal to the first threshold can be defined as the vicinity of the outer surface, and the region where the density is greater than or equal to the second threshold can be defined as the vicinity of the center. The first threshold can be defined, for example, as a value lower than the average value of the density of the entire magneto-optical material 10 by a specified value (for example, the standard deviation of the entire magneto-optical material 10 × γ (where γ is a positive real number, e.g., 0.5)). The second threshold can be defined, for example, as a value higher than the average value of the density of the entire magneto-optical material 10 by a specified value (for example, the standard deviation of the entire magneto-optical material 10 × δ (where δ is a positive real number, e.g., 0.5)). γ and δ may be the same or different. Also, a portion of the range of the vicinity of the outer surface and a portion of the range of the vicinity of the center may overlap. The neighborhood of the outer surface and the neighborhood of the center may or may not be adjacent to each other.

[0025] Furthermore, for example, if the second density is lower than the first density, the discrete or continuous distribution of density in a specified direction in the magneto-optical material 10 can be calculated, and the region where the density is equal to or greater than the second threshold can be defined as the vicinity of the outer surface, and the region where the density is equal to or less than the first threshold can be defined as the vicinity of the center. The first threshold can be set, for example, as a value lower than the average value of the density of the entire magneto-optical material 10 by a specified value (for example, the standard deviation of the entire magneto-optical material 10 × γ (where γ is a positive real number, e.g., 0.5)). The second threshold can be set, for example, as a value higher than the average value of the density of the entire magneto-optical material 10 by a specified value (for example, the standard deviation of the entire magneto-optical material 10 × δ (where δ is a positive real number, e.g., 0.5)). γ and δ may be the same or different. Also, a part of the vicinity of the outer surface and a part of the vicinity of the center may overlap. The vicinity of the outer surface and the vicinity of the center may be adjacent to each other or not.

[0026] The discrete or continuous distribution of density in a specified direction is calculated, for example, from the area occupancy rate of discrete or continuous nanoparticles 12 in a specified direction, determined after an SEM image of the magneto-optical material 10 is acquired and the matrix 11 and nanoparticles 12 are identified from a group of pixels having equal components in the specified direction of the SEM image, or from the volume occupancy rate determined from said area occupancy rate.

[0027] In a preferred embodiment, as shown in Figure 1, the magneto-optical material 10 has a second density, which is the density of nanoparticles 12 near the center of the magneto-optical material, which is the density of nanoparticles 12 near the outer surface of the magneto-optical material 10. In this case, the ratio of the second density to the first density (second density / first density, hereinafter referred to as "density ratio") is preferably greater than 1.0, and more preferably 1.14 or greater.

[0028] In another preferred embodiment, the magneto-optical material 10 has a second density, which is the density of nanoparticles 12 near the center of the magneto-optical material, which is the density of nanoparticles 12 near the outer surface of the magneto-optical material 10, which is the first density, which is the density of nanoparticles 12 near the outer surface of the magneto-optical material 10, as shown in Figure 2. In this case, the density ratio is preferably less than 1.0, and more preferably 0.88 or less.

[0029] Here, the density of nanoparticles 12 represents the mass or number of nanoparticles 12 per unit volume of the magneto-optical material 10. Preferably, the first density is calculated as the average density of a range defined as the vicinity of the outer surface, and the second density is calculated as the average density of a range defined as the vicinity of the center.

[0030] In calculating the density ratio, the density ratio may be calculated by using a physical quantity proportional to density as a substitute for density, without calculating the values ​​of the first and second densities separately. Since the same proportionality constant exists in both the numerator and denominator when calculating the density ratio, the proportionality constant itself cancels out. Therefore, the density ratio may be calculated by using a physical quantity proportional to density as a substitute for the values ​​of the first and second densities. Examples of physical quantities proportional to density include sputter power ratio, mass fraction, or volume fraction. Furthermore, when calculating the density ratio, the proportionality constant of the physical quantity proportional to density may or may not be calculated.

[0031] For example, the sputtering power ratio (the ratio of the sputtering power of the nanoparticle target to the sputtering power of the matrix target) is a physical quantity that is proportional to density. This is because the deposition rate of the magneto-optical material 10 is proportional to the power input to the target. Therefore, the density of nanoparticles 12 may be determined according to the sputtering power ratio. By adjusting the power input to the target, the deposition rates of the material constituting the nanoparticles 12 and the material constituting the matrix 11 can be controlled, thereby controlling the volume fraction of the nanoparticles 12 and the matrix 11 in the film of the magneto-optical material 10 and changing their respective density ratios. In this case, for example, the sputtering power ratio at the beginning of sputtering may be calculated as a substitute for the first density, the sputtering power ratio at half the time of sputtering deposition may be calculated as a substitute for the second density, and the ratio of the sputtering power ratio at the beginning of sputtering to the sputtering power ratio at half the time of sputtering deposition may be calculated as the density ratio. Furthermore, the density of the nanoparticles 12 may be calculated based on the number of nanoparticles 12 per unit volume of the magneto-optical material 10 as a number density or a physical quantity proportional to the number density.

[0032] (Manufacturing method) The magneto-optical material 10 of the present invention is deposited on a substrate 20. The substrate 20 can be a quartz glass or a glass substrate such as Corning's #7059 (Corning's trade name), a single-crystal Si wafer or MgO substrate with a thermally oxidized surface, or the like.

[0033] As shown in Figure 3, for example, a magnetic metal target is used as the first target 41 constituting the nanoparticles 12, and a target is used as the second target 42 constituting the matrix 11, and the magneto-optical material 10 is deposited by sputtering. The first target and the second target are cathodes in the sputtering method. Note that the first target 41 and the second target 42 may each be composed of multiple targets. In this case, the magneto-optical material 10 is deposited by sputtering while adjusting factors such as the sputtering power and sputtering power supply time of each target in order to adjust the composition ratio of the magneto-optical material 10.

[0034] The process for producing the magneto-optical material 10 includes the steps of generating sputtered particles from the first target 41 and the second target 42, respectively, by independently controlling the power supplied to each of the first target 41 and the second target 42, which are arranged in the chamber 40, and the steps of rotating the anode 44 so that the substrate 20 supported by the anode 44 passes periodically to the position into which the sputtered particles emitted from the first target 41 and the second target 42 are incident.

[0035] In Figure 3, the first target 41 and the second target 42 are held facing downwards, and the anode 44 is held facing upwards, so that the first target 41 and the second target 42 are positioned opposite to the anode 44. Alternatively, the first target 41 and the second target 42 may be held facing upwards, and the anode 44 may be held facing downwards, so that the first target 41 and the second target 42 are positioned opposite to the anode 44. Furthermore, the first target 41 and the second target 42 may be positioned not opposite to the anode 44.

[0036] The materials constituting the first target 41 and the second target 42 are sputtered under controlled conditions such as sputtering power and sputtering power supply time, and partially free-radicalized sputtered particles are ejected from the first target 41 and the second target 42, respectively. The negatively charged sputtered particles are electrically attracted to the anode 44, and the magneto-optical material 10 is fabricated to have density variations in a specified direction.

[0037] The sputtering power supplied to the first target 41 and the second target 42 is independently controlled by the first power supply device 410 and the second power supply device 420, respectively, so as to correspond to a composition in which the materials of the first target 41 and the second target 42 have density differences in a specified direction. Sputtered particles simultaneously sputtered from the first target 41 and the second target 42 reach the substrate 20 supported by the anode 44, and a magneto-optical material with a desired density ratio is fabricated. A film with the desired composition is formed as the substrate 20 periodically passes near the first target 41 and the second target 42. In order to control the incident angle of the sputtered particles, the relationship between the opposing arrangement of the first target 41 and the second target 42 and the anode 44 may be controlled by setting an arbitrary angle on the first target 41 and the second target 42 or the substrate 20, within a range in which magnetic anisotropy derived from the film structure is maintained. Similarly, even in the case of non-opposing arrangement, a film with the desired composition is formed as the substrate 20 periodically passes through the position where it contacts the sputtered particles.

[0038] The anode 44 is rotationally driven at a constant or variable speed within the range of preferably 5 rpm to 60 rpm, more preferably 7 rpm to 56 rpm, and even more preferably 12 rpm to 56 rpm.

[0039] Ar gas is used as the atmosphere during sputter deposition. The film thickness is controlled by the deposition time, for example, to produce magneto-optical materials 10 with a thickness of 0.3 to 10.0 μm. In the deposition process, the temperature of the substrate is preferably controlled to a first temperature within the range of 200 to 800°C, more preferably 300 to 600°C, and even more preferably 450 to 550°C. The atmospheric pressure of the substrate (including the region) is preferably controlled to 2.0 Pa or less, more preferably 0.3 to 1.5 Pa, and even more preferably 0.5 to 1.1 Pa. The reason for controlling the temperature and pressure in this way is to suppress the decrease in the crystallinity of the matrix and the resulting decrease in transmittance due to the influence of impurity contamination. Furthermore, after deposition, 1 × 10 -4The heat treatment is performed in a vacuum of Pa or less while applying a magnetic field of 1 to 10 kOe. The heat treatment temperature is preferably controlled to a range of 300 to 700°C, more preferably 400 to 600°C, and even more preferably 450 to 550°C.

[0040] The sputtering power during film deposition is controlled for both the first and second targets. The sputtering power applied to the first target is referred to as the first sputtering power, and the sputtering power applied to the second target is referred to as the second sputtering power. In this case, the ratio of the first sputtering power to the second sputtering power (first sputtering power / second sputtering power, hereinafter referred to as the "sputtering power ratio") is controlled over time to create a desired density distribution of nanoparticles 12 present in the matrix 11 in a specified direction. The sputtering power ratio may be changed continuously or intermittently with respect to time. [Examples]

[0041] On the substrate 20, magneto-optical materials 10 as Examples 1 to 5 were manufactured by sputtering, with the second density (density of nanoparticles 12 near the center) being higher than the first density (density of nanoparticles 12 near the outer surface) being higher than the first density (density of nanoparticles 12 near the outer surface) being higher than the first density (density of nanoparticles 12 near the outer surface) being higher than the first density (density of nanoparticles 12 near the outer surface) being higher than the first density (density of nanoparticles 12 near the center) being higher than the first density (density of nanoparticles 12 near the outer surface) being higher than the second density (density of nanoparticles 12 near the center) being higher than the first density (density of nanoparticles 12 near the outer surface first density (density of nanoparticles 12 near the outer surface) being higher than the first density (density of nanoparticles 12 near the outer surface) being higher than the first density Based on a constant sputtering power ratio, the first power supply device 410 and the second power supply device 420 were controlled, and the magneto-optical material 10 as Comparative Example 1 was manufactured. The film deposition conditions for Examples 1 to 11 and the Comparative Example are shown in Table 1.

[0042] [Table 1]

[0043] As the substrate 20, a quartz substrate approximately 0.5 mm thick or a Corning #7059 (Corning product name) glass substrate was used. Table 2 shows the film thickness, average values ​​of atomic ratios a, b, c, w, x, y, and z representing the composition of the thin films for each example and comparative example, and the density ratio based on the sputtering power ratio. Since the sputtering power ratio is proportional to the density of nanoparticles 12, the sputtering power ratio ratio was calculated as the density ratio of nanoparticles 12. Here, the sputtering power ratio at the beginning of sputtering was calculated as a substitute for the first density. Also, the sputtering power ratio at half the time of sputtering deposition was calculated as a substitute for the second density. The density ratio was calculated as the ratio of the sputtering power ratio at the beginning of sputtering to the sputtering power ratio at half the time of sputtering deposition. Here, the specified direction is the film thickness direction.

[0044] [Table 2]

[0045] Table 2 shows the compositional configurations of Examples 1-11 and Comparative Example 1, as well as the Figure of Merit (FOM) of the magneto-optical material 10. The FOM for the magneto-optical material 10 is defined as Faraday rotation angle (θ) / (optical path length (d) × optical transmittance (T)). Table 1 shows the FoM at 1550 nm with magnetic fields of 0.5 k and 1.0 k (Oe). Here, the optical transmittance is the optical transmittance in the specified direction (film thickness direction).

[0046] Referring to Table 2, Examples 1 to 11 show superior Faraday rotation angle compared to Comparative Example 1. Therefore, each of Examples 1 to 11 can further increase the Faraday rotation angle compared to the conventional magneto-optical material 10, and consequently improve the sensitivity of the magneto-optical material 10.

[0047] Figure 6 shows the magnetic field dependence of the Faraday rotation angle for incident light at a wavelength of 1550 nm in Examples 5, 8, and Comparative Example 1. Referring to Figure 6, it is clear that the saturation value of the Faraday rotation angle in Example 5 is larger than that of Comparative Example 1. Furthermore, even at low magnetic fields (-4.0 to 4.0 kOe), the Faraday rotation angles in Examples 5 and 8 were larger than those of Comparative Example 1.

[0048] As described above, by arranging the magnetic nanoparticles 12 so that they are densely packed and sparse in the film thickness direction, the demagnetizing field of the magneto-optical material 10 in the film thickness direction is reduced. This increases the internal magnetic field and suppresses the decrease in the Faraday rotation angle.

[0049] Beyond the embodiments and examples described above, other embodiments of the present invention are possible, and their details can be improved in various obvious ways. The present invention can be modified and altered within the bounds of what is easily accessible to those skilled in the art. Accordingly, the foregoing disclosures, descriptions, and drawings are for illustrative purposes only and do not in any way limit the present invention as defined solely by the claims. [Explanation of Symbols]

[0050] 10...Magneto-optical material, 11...Matrix, 12...Nanoparticles, 20...Substrate, 40...Chamber, 41...First target, 42...Second target, 44...Anode, 410...First power supply device, 420...Second power supply device

Claims

1. In a magneto-optical material having a nanogranular structure in which nanoparticles are dispersed in a matrix, The matrix is ​​a fluoride, oxide, or nitride matrix containing at least one element selected from the group consisting of Li, Be, Mg, Al, Si, Ca, Sr, Ba, Bi, Ti, rare earth elements, Zr, Nb, Hf, and Ta. The nanoparticles are magnetic nanoparticles comprising a metal having at least one magnetization selected from the group consisting of particles of at least one metal or alloy selected from Fe, Co, and Ni. The distribution of the nanoparticles present in the matrix in a specified direction is dense and sparse. Magneto-optical materials.

2. In the magneto-optical material according to claim 1, The second density, which is the density of nanoparticles near the center of the magneto-optical material, is higher than the first density, which is the density of nanoparticles near the outer surface of the magneto-optical material. Magneto-optical materials.

3. In the magneto-optical material according to claim 2, The ratio of the second density to the first density (second density / first density) is 1.14 or greater. Magneto-optical materials.

4. In the magneto-optical material according to claim 1, The second density, which is the density of nanoparticles near the center of the magneto-optical material, is lower than the first density, which is the density of nanoparticles near the outer surface of the magneto-optical material. Magneto-optical materials.

5. In the magneto-optical material according to claim 4, The ratio of the second density to the first density (second density / first density) is 0.88 or less. Magneto-optical materials.

6. In the magneto-optical material according to claim 1, The density of the aforementioned nanoparticles gradually decreases or increases in a specified direction. Magneto-optical materials.

7. A method for manufacturing a magneto-optical material according to any one of claims 1 to 6, The process includes a step of producing a nanogranular material having a nanogranular structure by controlling the amount of power supplied to a first target constituting the nanoparticles and the amount of power supplied to a second target constituting the matrix, such that the nanoparticles dispersed in the matrix are adjusted to a specified density. A method for manufacturing magneto-optical materials.

Images