Magnetic body

Abstract

To provide a magnetic material that can be manufactured even under normal temperature and pressure conditions. [Solution] A magnetic material 1 including a magnetic layer 3, wherein the magnetic layer 3 has magnetic anisotropy and an fcc structure. Furthermore, since the magnetic layer 3 can be formed by deposition by electrolytic deposition, it can be manufactured at room temperature and pressure without using the sputtering method.

Description

[Technical Field]

[0001] This invention relates to magnetic materials. [Background technology]

[0002] Conventionally, magnetic materials used in various devices such as magnetic memory are known to be magnetic materials in which a magnetic layer is formed on the surface of a substrate using a sputtering method (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-094193 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, the sputtering method requires the fabrication of a magnetic layer on a substrate at high temperatures within a vacuum chamber, resulting in large equipment and a heavy workload during the manufacturing process. Therefore, there is a need for the development of new technologies that can fabricate magnetic materials at room temperature and pressure without using the sputtering method.

[0005] The present invention has been made in view of the above points, and aims to provide a magnetic material that can be manufactured even at room temperature and pressure. [Means for solving the problem]

[0006] The present invention relates to a magnetic material comprising a magnetic layer, wherein the magnetic layer has magnetic anisotropy and an fcc structure. [Effects of the Invention]

[0007] According to the present invention, since the magnetic layer can be formed by depositing it by electrolytic deposition, it can be manufactured at room temperature and pressure without using the sputtering method.

Brief Description of the Drawings

[0008] [Figure 1] It is a schematic diagram showing the overall structure of the magnetic material in the first embodiment. [Figure 2] It is an AFM image of the surface of the magnetic layer in the first embodiment. [Figure 3] 3A is a TEM image of the cross-section of the magnetic material in the first embodiment, and 3B is a TEM image obtained by magnifying a partial region of 3A. [Figure 4] 4A to 4D are EDS mapping images of the cross-section of the magnetic material in the first embodiment. [Figure 5] 5A and 5B are atomic-resolution EDS images of the cross-section of the magnetic material in the first embodiment. [Figure 6] 6A is an EDS mapping image of the cross-section of the magnetic material in the first embodiment, and 6B is a graph showing the EDS composition analysis result of 6A. [Figure 7] 7A is a HR-TEM image of the cross-section of the magnetic material in the first embodiment, and 7B is a HR-TEM image obtained by magnifying the region surrounded by the solid line in 7A. [Figure 8] It is a graph showing the magnetization curve of the magnetic material in the first embodiment. [Figure 9] It is a table showing the manufacturing conditions in the electrodeposition of the magnetic layer in the first embodiment. [Figure 10] 10A is a graph showing the XRD measurement result of the magnetic material in the first embodiment, and 10B is a table showing the results of examining the diffraction angle 2θ [degree], the lattice constant a3 [nm], and the Co content [at.%] of the magnetic material when the electrodeposition time is changed. [Figure 11]11A is a graph showing the hysteresis curve of the Kerr rotation angle of a magnetic material when the electrodeposition time is 20 s, 11B is a graph showing the hysteresis curve of the Kerr rotation angle of a magnetic material when the electrodeposition time is 40 s, 11C is a graph showing the hysteresis curve of the Kerr rotation angle of a magnetic material when the electrodeposition time is 75 s, 11D is a graph showing the hysteresis curve of the Kerr rotation angle of a magnetic material when the electrodeposition time is 150 s, 11E is a graph showing the hysteresis curve of the Kerr rotation angle of a magnetic material when the electrodeposition time is 300 s, 11C' is a graph showing the magnetization curve of a magnetic material when the electrodeposition time is 75 s, 11D' is a graph showing the magnetization curve of a magnetic material when the electrodeposition time is 150 s, and 11E' is a graph showing the magnetization curve of a magnetic material when the electrodeposition time is 300 s. [Figure 12] 12A is a graph showing the dependence of the magnetization amount (saturation magnetization Ms × thickness t) in a magnetic material on the electrodeposition time, and 12B is a graph showing the dependence of the anisotropic magnetic field Hk, coercivity Hc, and nucleation magnetic field Hn in a magnetic material on the electrodeposition time. [Figure 13] This is a schematic diagram showing the overall configuration of the magnetic material in the second embodiment. [Figure 14] This is an AFM image of the surface of the magnetic material in the second embodiment. [Figure 15] 15A is an AFM image of the surface of the first magnetic layer of the magnetic material in the second embodiment, 15B is an AFM image of the surface of the second magnetic layer of the magnetic material, and 15C is an AFM image of the surface of the second magnetic layer when the first magnetic layer and the second magnetic layer are stacked. [Figure 16] 16A is a TEM image of a cross-section of a magnetic material in the second embodiment, and 16B is a TEM image of a magnified portion of 16A. [Figure 17] Figures 17A to 17D are EDS mapping images of the cross-section of the magnetic material in the second embodiment. [Figure 18] Figures 18A and 18B are atomic-resolution EDS images of the cross-section of the magnetic material in the second embodiment. [Figure 19]19A is an EDS mapping image of the cross-section of the magnetic material in the second embodiment, and 19B is a graph showing the EDS composition analysis results of 19A. [Figure 20] 20A is a cross-sectional view showing a cross-section of the magnetic material in the second embodiment, and 20B is a graph showing the XRD measurement results of the magnetic material. [Figure 21] 21A is a graph showing the magnetization curve of the first magnetic layer of the magnetic material in the second embodiment, 21B is a graph showing the magnetization curve of the second magnetic layer of the magnetic material, and 21C is a graph showing the magnetization curve when the first magnetic layer and the second magnetic layer are stacked. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, the same reference numerals are used for identical components, and redundant descriptions are omitted.

[0010] <First Embodiment> <Overall composition of magnetic material> As shown in Figure 1, the magnetic material 1 of the first embodiment has a substrate 2 and a magnetic layer 3 formed on the surface of the substrate 2. The substrate 2 is formed of a substrate forming material such as Pt, W, Ru, Pd, Au, or Cu. The substrate 2 may be a single-layer structure formed of the substrate forming material, or it may be a multi-layer structure in which multiple layers made of different materials are stacked.

[0011] The substrate 2 may have an amorphous structure, but it is preferable that it has a crystalline structure. When the substrate 2 has a crystalline structure, it is preferable that the difference (a2-a3) between the lattice constant a2 of the substrate 2 and the lattice constant a3 of the magnetic layer 3 is 10% or less of the lattice constant a2 of the substrate 2. By making the difference between the lattice constant of the substrate 2 and the lattice constant of the magnetic layer 3 10% or less, the magnetic layer 3 can be formed while maintaining its crystalline structure when formed by electrolytic deposition.

[0012] The magnetic layer 3 has magnetic anisotropy and an fcc (face-centered cubic) structure (face-centered cubic lattice structure). Preferably, the magnetic layer 3 is formed from a Co alloy containing at least one of Pt, Au, Pd, and Cu. The Co content of the magnetic layer 3 is preferably 10 to 55 [at.%], and the value of the magnetic anisotropy constant Ku in the magnetic material 1 can be changed by changing the Co content. For example, if the Co content of the magnetic layer 3 is 10 to 20 [at.%], the magnetic anisotropy constant Ku becomes 1 × 10⁻⁶. 5 [erg·cm -3 It can also be made smaller than ]. On the other hand, if the Co of magnetic layer 3 is set to 45-55 [at.%], the magnetic anisotropy constant Ku can be set to 1 × 10 6 [erg·cm -3 It can also be made larger than ].

[0013] The magnetic layer 3 preferably has a roughness Ra of 2 nm or less, more preferably 1.5 nm or less, and most preferably 0.5 nm or less, when its surface is measured using an atomic force microscope (AFM). The magnetic material 1 can be used in magnetic memory elements and the like where surface planarization is desired by planarizing the surface of the magnetic layer 3. Furthermore, the magnetic layer 3 preferably has a thickness of 10 nm or less. The magnetic material 1 can change the magnetization amount (when saturation magnetization is Ms and the thickness of the magnetic layer 3 is t, it becomes saturation magnetization Ms × thickness t), anisotropy magnetic field Hk, coercivity Hc, and nucleation magnetic field Hn by adjusting the thickness of the magnetic layer 3.

[0014] <Method for manufacturing magnetic materials> Next, a method for manufacturing the magnetic material 1 will be described. First, a substrate 2 formed by a substrate forming member is prepared. Next, the substrate 2 is immersed in an electrodeposition bath containing Co (electrodeposition bath) (immersion step). Then, a magnetic layer 3 made of a Co alloy is formed on the surface of the substrate 2 immersed in the electrodeposition bath by constant potential electrodeposition at a predetermined electrodeposition potential (magnetic layer formation step). In this embodiment, a magnetic layer 3 having magnetic anisotropy and an fcc structure can be formed on the substrate 2 by electrodeposition. When forming the magnetic layer 3 on the surface of the substrate 2 by electrodeposition, it is preferable to control the crystal nucleation and deposition rate by adjusting the metal salt concentration of the electrodeposition bath.

[0015] The electrodeposition bath preferably contains a Co salt at a predetermined concentration, and further preferably contains at least one of Pt, Au, or Cu salts at a predetermined concentration. The electrodeposition bath preferably does not contain a complexing agent (e.g., sodium citrate, ammonium citrate, glycine, etc.) that coordinates with metal ions and changes the deposition potential, but contains a Co salt, and further preferably contains at least one of Pt, Au, or Cu salts. The concentration of the Co salt is preferably 1 to 10 [mM]. The concentration of the Pt, Au, or Cu salt is preferably 1 to 10 [mM].

[0016] It has been confirmed that the magnetic layer 3 according to this embodiment can be formed by electrolysis to a degree comparable to, or even better than, the sputtering method, resulting in a smoother surface. For example, when forming a magnetic layer 3 made of a CoPt alloy on the surface of a substrate 2 by electrolysis, the deposition of Pt occurs preferentially first, and relatively large crystal nuclei made of Pt are formed on the surface of the substrate 2. Subsequently, as the crystal nuclei made of Pt grow further, the number of Pt ions decreases on the surface of the substrate 2 where the crystal nuclei have grown, and the proportion of Co electrolytically deposited increases. Next, the crystal particles electrolytically deposited by Co coalesce to cover the crystal nuclei made of Pt, increasing the crystal size, and the crystals bond in the direction of the surface of the substrate 2, thereby forming the magnetic layer 3 on the surface of the substrate 2. In this case, by causing the crystal nuclei to be generated finely and densely, the roughness Ra of the surface of the magnetic layer 3 can be reduced, and the surface can be formed smoothly.

[0017] Here, it is known that the morphology of the precipitate depends on the metal ions near the electrode (e.g., R. Winand, Electrochimica Acta, Vol. 43, No. 19-20, pp. 2925-2932, 1998). When the metal ion concentration increases, the crystal nuclei become smaller, and a large number of small crystal nuclei can be generated. In this embodiment, it is preferable to increase the bath concentration and the concentration of the Pt salt to reduce the size of the Pt crystal nuclei that are initially generated.

[0018] The electrodeposition of the magnetic layer 3 on the surface of the substrate 2 is not limited to constant potential electrodeposition, in which the potential of the substrate 2 is kept constant, but may also be carried out by constant current electrodeposition, in which the reaction rate is constant. The electrodeposition potential when performing constant potential electrodeposition is preferably negative, as described above, and specifically, it is preferably -350 to -900 [mV vs. Ag / AgCl].

[0019] The electrodeposition time (electrodeposition time) is preferably 20 seconds or longer. The thickness of the magnetic layer 3 is proportional to the electrodeposition time, and the thickness can be increased by increasing the electrodeposition time. Verification tests described later have confirmed that as the thickness of such a magnetic layer 3 increases, the magnetization of the magnetic material 1 increases. Furthermore, verification tests described later have confirmed that as the thickness of the magnetic layer 3 increases, the anisotropy magnetic field Hk, coercivity Hc, and nucleation magnetic field Hn in the magnetic material 1 decrease.

[0020] Furthermore, in the manufacturing method of the magnetic material 1 according to this embodiment, when forming the magnetic layer 3 on the substrate 2, the composition of the Co alloy that becomes the magnetic layer 3 can be changed by changing the electrodeposition potential value described above. For example, when the electrodeposition potential is set to -350 to -900 [mV vs. Ag / AgCl], a magnetic layer 3 with a Co content of 10 to 55 [at.%] can be formed. Also, when the electrodeposition potential is set to -600 to -900 [mV vs. Ag / AgCl], a magnetic layer 3 with a Co content of 45 to 55 [at.%] can be formed, and when the electrodeposition potential is set to -350 to -450 [mV vs. Ag / AgCl], a magnetic layer 3 with a Co content of 10 to 20 [at.%] can be formed.

[0021] <AFM image of the magnetic layer surface> Next, following the manufacturing method described above, the magnetic layer 3 was actually fabricated by electrolysis, and the surface roughness Ra of the magnetic layer 3 was measured using an atomic force microscope (AFM) (Shimadzu Corporation SPM-9700). Here, a base was prepared by forming a 5 nm thick Ti film on a Si substrate, and a Pt substrate 2 (hereinafter referred to as the Pt substrate) was fabricated on the surface of the Ti film of the base by sputtering. The thickness of the Pt substrate was set to 15 nm. As a result, a magnetic material 1 including the magnetic layer 3 was obtained.

[0022] The electrodeposition bath was prepared using 1 mM CoSO4, 1 mM H₂PtCl₆, and 0.1 M Na₂SO4. The bath concentration was reduced to decrease the deposition rate. In addition, to avoid inhibiting Pt nucleation, no additives such as ammonium citrate or glycine were added to the electrodeposition bath. A mesh-structured counter electrode made of Pt and a reference electrode made of Ag / AgCl were placed inside the electrolytic cell. The Pt substrate was then immersed in the electrodeposition bath inside the electrolytic cell, and constant potential electrodeposition was performed at room temperature and pressure with an electrodeposition potential of -650 mV (-650 mV vs. Ag / AgCl) relative to the reference electrode. The electrodeposition time was 75 s, and a magnetic layer 3 was slowly deposited on the surface of the Pt substrate in the electrodeposition bath, forming a magnetic layer 3 made of CoPt alloy on the Pt substrate.

[0023] Then, when the surface of the obtained magnetic layer 3 was observed with AFM, the AFM image shown in Figure 2 was confirmed. The AFM image was obtained by measuring the central 1 [μm] square area of ​​the sample in tapping mode. From Figure 2, it was confirmed that the surface of the magnetic layer 3 has a roughness Ra of 0.43 [nm]. Furthermore, it was confirmed that the magnetic layer 3 is formed smoothly with few irregularities. In conventional manufacturing methods for producing magnetic layers (e.g., sputtering method), it is difficult to form a smooth surface of the magnetic layer under normal temperature and pressure, and it is difficult to obtain a magnetic layer 3 with a smooth surface like the one shown in Figure 2.

[0024] <TEM image of a cross-section of a magnetic material> Next, the cross-section of magnetic material 1, created using the "AFM image of the surface of the magnetic layer" described above, was observed using a transmission electron microscope (TEM). In this case, a Ni coating was formed on the surface of magnetic layer 3 to clarify its contour. The Ni coating was formed using a turbo sputter coater (K575XD high-performance turbo sputter coater manufactured by Emitec, UK). The resulting cross-section of magnetic material 1 was then observed using a TEM (Spectra Ultra manufactured by Thermo Fisher Scientific), yielding the TEM image shown in Figure 3A. Figure 3B is a magnified TEM image of a portion of 3A.

[0025] The TEM image shown in Figure 3A confirms that a Pt substrate 2 is formed as the substrate on the surface of a base on which a Ti film 4 is formed on a Si substrate 5. Furthermore, it was confirmed that a magnetic layer 3 made of a CoPt alloy is formed in layers on the surface of substrate 2. A Ni coating 6 is formed on the surface of the magnetic layer 3.

[0026] Specifically, as shown in Figures 3A and 3B, it was confirmed that a magnetic layer 3 was formed from a CoPt alloy with a thickness of 5 nm (hereinafter also referred to as the CoPt layer). Furthermore, it was confirmed that there was no dead layer between the CoPt layer 3 and the Pt substrate 2, and that the CoPt alloy was neatly stacked on the Pt substrate 2 without any gaps. In addition, it was confirmed in Figures 3A and 3B that the surface of the CoPt layer 3 was smooth.

[0027] <EDS mapping image of a cross-section of a magnetic material> Next, the cross-section of magnetic material 1, created using the "AFM image of the surface of the magnetic layer" method described above, was examined using energy dispersive X-ray spectroscopy (EDS) to obtain EDS mapping images, resulting in the results shown in Figures 4A to 4D.

[0028] Figure 4A shows a TEM image of the cross-section of magnetic material 1, and Figure 4B shows an EDS mapping image of Co and Pt mapped in correspondence with magnetic material 1 shown in Figure 4A. Figure 4C shows an EDS mapping image of only Co mapped in correspondence with magnetic material 1 shown in Figure 4A, and Figure 4D shows an EDS mapping image of only Pt mapped. According to the EDS mapping images shown in Figures 4B to 4D, it was confirmed that Co and Pt are uniformly distributed in magnetic layer 3, and that a uniform CoPt layer is formed.

[0029] <Atomic-resolution EDS image of a cross-section of a magnetic material> Next, in order to further magnify the cross-section of magnetic material 1 created in the "<AFM image of the surface of the magnetic layer>" described above and observe the magnetic layer 3 at the atomic level, the cross-section of magnetic material 1 was examined using an atomic-resolution EDS image, and the results shown in Figures 5A and 5B were obtained. From Figure 5A, it was confirmed that the Pt atoms of substrate 2 and the Co alloy atoms of magnetic layer 3 are arranged in a regular manner. Figure 5B is an atomic-resolution EDS image showing Co and Pt in different colors, and it is possible to determine whether the atoms are Pt or Co from the color scheme. From Figure 5B, it was confirmed that in substrate 2, the color indicating Pt appears, and it was confirmed that the Pt atoms are arranged in a regular manner. In addition, in magnetic layer 3, the color indicating Co and the color indicating Pt are uniformly mixed within the layer, so it was confirmed that the Co atoms and Pt atoms are uniformly distributed within the layer. From this, it was confirmed that an alloy is formed of Co and Pt in magnetic layer 3.

[0030] <EDS mapping image and EDS compositional analysis results of a cross-section of a magnetic material> Next, EDS compositional analysis was performed on the cross-section of magnetic material 1 created using the "AFM image of the surface of the magnetic layer" described above, and the results shown in Figures 6A and 6B were obtained. EDS compositional analysis is performed by irradiating magnetic material 1 with an electron beam using a TEM equipped with EDS, which generates characteristic X-rays of the elements contained in magnetic material 1. The intensity of the characteristic X-rays of the elements detected by the X-ray detection unit is correlated with the composition ratio of the elements contained in magnetic material 1 to determine the compositional ratio.

[0031] Figure 6A shows an EDS mapping image of the cross-section of magnetic material 1, and Figure 6B shows the EDS composition analysis results, plotting the elemental composition in the region enclosed by the solid line in 6A, corresponding to each layer of the EDS mapping image. From Figures 6A and 6B, the composition of magnetic layer 3 (CoPt layer (thickness 5 [nm])) is Co 48 Pt 52 It was confirmed that this was the case.

[0032] <HR-TEM image of a cross-section of a magnetic material> Next, the cross-section of magnetic material 1, created using the "AFM image of the surface of the magnetic layer" described above, was observed using a high-resolution transmission electron microscope (HR-TEM), and the HR-TEM image shown in Figure 7A was obtained. The HR-TEM used was a Thermo Fisher Scientific Spectra Ultra. Figure 7B is an enlarged HR-TEM image of a portion of the area enclosed by the solid line in 7A.

[0033] From Figures 7A and 7B, the atomic arrangement of the cross-section of the substrate 2, a Pt substrate, was examined, and it was confirmed that the atoms of substrate 2 are stacked in an fcc(111) orientation perpendicular to the plane. Furthermore, from Figures 7A and 7B, the atomic arrangement of the cross-section of the magnetic layer 3, a CoPt layer, was examined, and it was confirmed that the atoms of magnetic layer 3 are stacked in an fcc(111) orientation perpendicular to the plane. It was also confirmed that the atoms of magnetic layer 3 grow epitaxially from substrate 2 and are continuously arranged in an fcc structure from substrate 2. The high anisotropy of magnetic layer 3 is due to the neat alignment of the interface with substrate 2, and it is thought that the smoothness is achieved by the stacking of atoms in an fcc (structure) perpendicular to the plane within magnetic layer 3.

[0034] <Magnetic curve of magnetic material (Magnetic M-magnetic field H curve)> Next, the magnetic properties of magnetic material 1, created using the "AFM image of the surface of the magnetic layer" described above, were evaluated using a magnetization curve (magnetization M-magnetic field H curve). The magnetization curve was measured using a vibrating sample magnetometer (VSM: Vibrating Sample Magnetometer, RIKEN BHV-3,5 Series) with a maximum magnetic field of 20 [kOe] (input value). Figure 8 shows the results of measurements for the out-of-plane and in-plane magnetization curves of magnetic layer 3. From the shape of the out-of-plane magnetization curve in Figure 8, perpendicular magnetic anisotropy was observed in magnetic layer 3, which is made of CoPt alloy. Furthermore, from the magnetization curve in Figure 8, the magnetic anisotropy constant Keff of magnetic layer 3 is 1.9 [Merg·cm]. -3, the saturation magnetization Ms is 620 [emu·cm -3 was confirmed, and it was found to have a large magnetic anisotropy. Note that the magnetic layer 3 from which the measurement results in FIG. 8 were obtained has perpendicular magnetic anisotropy, but it is not limited thereto and may be horizontal.

[0035] <Crystal Structure and Magnetic Properties of Magnetic Layer When Electrolysis Time is Changed> Next, under the manufacturing conditions described in the above-mentioned "<AFM Image of Surface of Magnetic Layer>", as shown in FIG. 9, the electrolysis time was changed between 20 and 300 [s] to form the magnetic layer 3, and the crystal structure, magnetic properties, etc. were investigated. First, the thicknesses of the magnetic layer 3 when the electrolysis times were 75 [s], 150 [s], and 300 [s] were measured from the TEM images and compared. When the electrolysis time was 75 [s], the thickness of the magnetic layer 3 was 5 [nm], when the electrolysis time was 150 [s], the thickness of the magnetic layer 3 was 10 [nm], and when the electrolysis time was 300 [s], the thickness of the magnetic layer 3 was 20 [nm]. It was confirmed that the thickness of the magnetic layer 3 increased as the electrolysis time became longer.

[0036] Then, for the magnetic layer 3 when the electrolysis times were changed to 75 [s], 150 [s], and 300 [s], X-ray diffraction (XRD: X-ray Diffraction) was measured with an X-ray diffractometer, and the results shown in 10A of FIG. 10 were obtained. For any magnetic layer with a changed electrolysis time, peaks of fcc CoPt(111) and fcc CoPt(222) were confirmed. On the other hand, L 11No peaks for ordered alloys were observed. Therefore, it was confirmed that magnetic layer 3 has an fcc structure regardless of its thickness. Furthermore, when the electrodeposition time was changed to 75[s], 150[s], and 300[s], the diffraction angle 2θ[degree], lattice constant a3[nm], and Co content[at.%] were investigated for magnetic layer 3, and the results shown in Figure 10, 10B were obtained. From Figures 10, 10A and 10B, it was confirmed that the peak of fcc CoPt(111) shifted to the higher angle side with increasing electrodeposition time, and from 10B, the lattice constant a3 decreased. It is thought that when the thickness (film thickness) is thin, the crystal of magnetic layer 3 is strained by the substrate 2, and as the thickness (film thickness) increases, the strain is relieved. The difference in lattice constants (a2-a3) between substrate 2 and magnetic layer 3 was 2% at 75 s, 4% at 150 s, and 4% at 300 s.

[0037] Furthermore, the lattice constant a of the fccPt used as substrate 2 was 0.391 [nm]. From this, it was confirmed that the difference between the lattice constant a of the fccPt used as substrate 2 and the lattice constant a of each magnetic layer 3 with different electrodeposition times was 0.02 [nm] or less.

[0038] Next, the hysteresis curves and magnetization curves of the Kerr rotation angle of magnetic material 1 were investigated when the electrodeposition time was set to 20[s], 40[s], 75[s], 150[s], and 300[s]. These were evaluated using a vibrating sample magnetometer (VSM) and a polar Kerr effect measuring device (NeoArk BH-810CPC-WU, light source wavelength 470nm). Figure 11 shows the hysteresis curve of the Kerr rotation angle of magnetic material 1 when the electrodeposition time is 20 [s], 11B shows the hysteresis curve of the Kerr rotation angle of magnetic material 1 when the electrodeposition time is 40 [s], 11C shows the hysteresis curve of the Kerr rotation angle of magnetic material 1 when the electrodeposition time is 75 [s], 11D shows the hysteresis curve of the Kerr rotation angle of magnetic material 1 when the electrodeposition time is 150 [s], and 11E shows the hysteresis curve of the Kerr rotation angle of magnetic material 1 when the electrodeposition time is 300 [s].

[0039] Figures 11A to 11E show the measurement results for the thickness of the magnetic layer 3 for each electrodeposition time. When the electrodeposition time was 20 [s], the thickness of the magnetic layer 3 was 1.4 [nm], and for the other electrodeposition times, the thicknesses of the magnetic layer 3 were 2.7 [nm], 5 [nm], 10 [nm], and 20 [nm], respectively. Figure 11C' is a graph showing the magnetization curve of the magnetic material 1 when the electrodeposition time was 75 [s], 11D' is a graph showing the magnetization curve of the magnetic material 1 when the electrodeposition time was 150 [s], and 11E' is a graph showing the magnetization curve of the magnetic material 1 when the electrodeposition time was 300 [s].

[0040] Figure 11 confirms that even when the electrodeposition time is changed, the hysteresis curve and magnetization curve of the Kerr rotation angle exhibit a PMA loop for all magnetic materials 1. In particular, the PMA loop was observed even with a thin magnetic layer 3 thickness of 1.4 [nm]. Furthermore, calculating the saturation magnetization Ms from 11C and 11C' in Figure 11 yields 620 [emu·cm]. -3 It was confirmed that as the thickness of the magnetic layer 3 of magnetic material 1 increased, the shape of the PMA loop became longer vertically and narrower horizontally. From this, it was found that the coercivity Hc and nucleation magnetic field Hn were maximum at 40 [s] and decreased with increasing electrodeposition time.

[0041] Next, we investigated the magnetization (saturation magnetization Ms × thickness t) of magnetic material 1 when the electrodeposition time was set to 75 [s], 150 [s], and 300 [s], and obtained the results shown in Figure 12, 12A. From Figure 12, 12A, it was confirmed that in magnetic material 1, as the electrodeposition time increased and the thickness of the magnetic layer 3 increased, the saturation magnetization Ms × thickness t increased linearly. This confirmed that the magnetization increased in proportion to the increase in the amount of CoPt deposited.

[0042] Next, the anisotropic magnetic field Hk, coercivity Hc, and nucleation magnetic field Hn of magnetic material 1 were investigated when the electrodeposition time was set to 75 [s], 150 [s], and 300 [s], and the results shown in Figure 12, 12B were obtained. From Figure 12, 12B, it was confirmed that in magnetic material 1, as the electrodeposition time increases and the thickness of the magnetic layer 3 increases, the anisotropic magnetic field Hk, coercivity Hc, and nucleation magnetic field Hn each decrease. Note that the magnetic layer 3 was, for example, a Co[n] with an electrodeposition time of 75 [s] and a thickness of 5 [nm]. 47 Pt 53 In this case, the saturation magnetization Ms is 630 [emu·cm] -3 The magnetic anisotropy constant Ku is 4.4 [Merg·cm]. -3 The effective magnetic anisotropy constant Keff acting on the magnetic layer 3 is 1.9 × 10⁻⁶. 6 [erg·cm -3 The coercivity Hc was 2.4 [kOe] and the nucleation magnetic field Hn was 2.0 [kOe]. Furthermore, it was confirmed that by further shortening the electrodeposition time, it is possible to fabricate an extremely thin perpendicular magnetization film with a nucleation magnetic field Hn of 3.0 [kOe] or higher and a magnetic layer 3 thickness of 3 [nm] or less.

[0043] Furthermore, for magnetic material 1 with electrodeposition times of 75[s], 150[s], and 300[s], the effective magnetic anisotropy constant Keff (Keff=Ku-2πMs) acting on the magnetic layer 3 is given. 2 When we investigated the following, we obtained the results shown in Table 1 below. The effective magnetic anisotropy constant Keff was calculated from the area difference between the perpendicular and in-plane magnetization curves. As shown in Table 1, it was confirmed that the effective magnetic anisotropy constant Keff decreases as the thickness (film thickness) of the magnetic layer 3 increases. Since the crystal is more strained at thinner film thicknesses, it is thought that strain contributes to the magnetic anisotropy. [Table 1]

[0044] <Mechanism and Effects> As described above, the magnetic material 1 has a configuration in which a magnetic layer 3 is provided on a substrate 2, and the magnetic layer 3 has magnetic anisotropy and an fcc structure. A magnetic material 1 having such a configuration can be formed by depositing the magnetic layer 3 by electrodeposition, and unlike when formed by the sputtering method, it can be manufactured at room temperature and pressure. Even when the thickness of the magnetic layer 3 is formed to be extremely thin, for example, 5 nm, the surface roughness Ra of the magnetic layer 3 can be formed to 0.5 nm or less. Such a magnetic material 1 can have a smooth surface while keeping the thickness of the magnetic layer 3 thin.

[0045] In magnetic material 1, the Co content of the magnetic layer 3 can be adjusted by adjusting the electrodeposition potential when forming the magnetic layer 3 on the surface of substrate 2 by electrodeposition. Furthermore, in magnetic material 1, the value of the magnetic anisotropy constant Ku can be changed by adjusting the Co content of the magnetic layer 3. For example, if the Co content of the magnetic layer 3 is 10 to 20 [at.%], the magnetic anisotropy constant Ku can be set to 1 × 10⁻¹⁰. 5 [erg·cm -3 It can also be made smaller than ]. On the other hand, if the Co of magnetic layer 3 is set to 45-55 [at.%], the magnetic anisotropy constant Ku can be set to 1 × 10 6 [erg·cm -3 It can also be made larger than ]. In this way, in magnetic material 1, the magnetic anisotropy constant Ku can be changed even if the thickness of the magnetic layer 3 is the same, so it can be applied with the optimal magnetic anisotropy constant Ku according to the thickness of each part, such as the memory layer of a magnetic memory element.

[0046] <Second Embodiment> <Overall composition of magnetic material> In the first embodiment described above, a magnetic body 1 was described in which a magnetic layer 3 was formed on the surface of a substrate 2. However, the present invention is not limited to this, and for example, as shown in Figure 13, a magnetic body 10 may be provided in which a plurality of magnetic layers 31, 32 are formed on the surface of a substrate 2. The magnetic body 10 according to the second embodiment will be described below. In this case, the substrate 2 has the same configuration as in the first embodiment, so its description will be omitted. In the second embodiment, the magnetic layer 31 formed on the surface of the substrate 2 will be referred to as the first magnetic layer 31, and the magnetic layer 32 formed on the surface of the first magnetic layer 31 will be referred to as the second magnetic layer 32.

[0047] The first magnetic layer 31 and the second magnetic layer 32 have magnetic anisotropy and an fcc structure, similar to the first embodiment. Preferably, the first magnetic layer 31 and the second magnetic layer 32 are formed from a Co alloy containing at least one of Pt, Au, and Cu. In the magnetic material 10, the Co content differs between the first magnetic layer 31 and the second magnetic layer 32, and the magnetic anisotropy constant Ku is different between the first magnetic layer 31 and the second magnetic layer 32. For example, in the magnetic material 10, the Co content of one of the first magnetic layer 31 and the second magnetic layer 32 is set to 10-20 [at.%], and the magnetic anisotropy constant Ku is set to 1 × 10⁻⁶ 5 [erg·cm -3 It can be made smaller than ]. The magnetic material 10 has a Co content of 45-55 [at.%] in the remaining part of the second magnetic layer 32, one of the first magnetic layer 31 and the other magnetic layer 32, and a magnetic anisotropy constant Ku of 1 × 10 6 [erg·cm -3 It can be made larger than ].

[0048] When the first magnetic layer 31 and the second magnetic layer 32 are laminated, the surface of the second magnetic layer 32, which is the outermost surface, preferably has a roughness Ra of 2 nm or less, more preferably 1.5 nm or less, and most preferably 0.5 nm or less, as measured by AFM. The thickness of the first magnetic layer 31 and the second magnetic layer 32 is preferably 7 nm or less, and more preferably 5 nm or less. Furthermore, by adjusting the thickness of the first magnetic layer 31 and the second magnetic layer 32, the magnetization amount (saturation magnetization Ms × thickness t), anisotropy magnetic field Hk, coercivity Hc, and nucleation magnetic field Hn can be changed for each of the first magnetic layer 31 and the second magnetic layer 32 of the magnetic material 10.

[0049] <Method for manufacturing a magnetic material according to the second embodiment> Next, a method for manufacturing the magnetic material 10 according to the second embodiment will be described. The method for manufacturing the magnetic material 10 having the first magnetic layer 31 and the second magnetic layer 32 differs from the manufacturing method of the first embodiment described above in that the electrodeposition potential is changed when performing constant potential electrodeposition, but other manufacturing conditions are the same. Here, we will mainly focus on the differences from the first embodiment.

[0050] Similarly in the second embodiment, first, a substrate 2 formed by a substrate forming member is prepared. Next, the substrate 2 is immersed in an electrodeposition bath containing Co of the same composition as in the first embodiment, and a first magnetic layer 31 made of a Co alloy is formed on the surface of the substrate 2 by constant potential electrodeposition at a predetermined electrodeposition potential. Subsequently, while the substrate 2 with the first magnetic layer 31 formed on it is immersed in the electrodeposition bath, constant potential electrodeposition is performed by changing the electrodeposition potential. As a result, a second magnetic layer 32 made of a Co alloy and having a different Co content than the first magnetic layer 31 can be formed on the surface of the first magnetic layer 31.

[0051] In this way, in the second embodiment, a first magnetic layer 31 and a second magnetic layer 32 having magnetic anisotropy and an fcc structure can be formed sequentially by electrolytic deposition. Furthermore, in the second embodiment, by changing the electrodeposition potential without changing the electrodeposition bath, the proportion of Co that is electrolytically deposited can be changed, and a first magnetic layer 31 and a second magnetic layer 32 with fcc structures having different Co content can be formed. In the second embodiment as in the first embodiment, when forming the first magnetic layer 31 and the second magnetic layer 32 by electrolytic deposition, it is preferable to control the crystal nucleation and deposition rate by adjusting the metal salt concentration of the electrodeposition bath.

[0052] The electrodeposition bath preferably contains a Co salt at a predetermined concentration, and further preferably contains at least one of Pt, Au, or Cu salts at a predetermined concentration. The electrodeposition bath preferably does not contain additives that coordinate with metal ions and change the deposition potential (e.g., sodium citrate, ammonium citrate, glycine, etc.), but contains a Co salt, and further preferably contains at least one of Pt, Au, or Cu salts. The concentration of the Co salt is preferably 1 to 10 [mM]. The concentration of the Pt, Au, or Cu salt is preferably 1 to 10 [mM].

[0053] In the second embodiment, as in the first embodiment, the roughness Ra of the surfaces of the first magnetic layer 31 and the second magnetic layer 32 can be reduced by ensuring that crystal nuclei are generated finely and densely, thereby forming a smooth outer surface. As a result, the first magnetic layer 31 and the second magnetic layer 32 in the second embodiment can be formed with a smooth surface at room temperature and atmospheric pressure by forming them by electrolytic deposition.

[0054] The electrodeposition of the first magnetic layer 31 on the surface of the substrate 2, and the electrodeposition of the second magnetic layer 32 on the surface of the first magnetic layer 31, are not limited to constant potential electrodeposition in which the potential of the substrate 2 is kept constant, but may also be carried out by constant current electrodeposition in which the reaction rate is constant. The electrodeposition potential when performing constant potential electrodeposition is preferably negative, as described above, and specifically, it is preferably -350 to -900 [mV vs. Ag / AgCl]. The bath temperature was set to room temperature.

[0055] In the manufacturing method of the magnetic material 10 according to the second embodiment, when forming the first magnetic layer 31 on the substrate 2, for example, by setting the first electrodeposition potential to -600 to -900 [mV vs. Ag / AgCl], the first magnetic layer 31 with a Co content of 45 to 55 [at.%] can be formed on the surface of the substrate 2. The first magnetic layer 31 has a magnetic anisotropy constant Ku of 1 × 10⁻¹⁵ due to the Co content being 45 to 55 [at.%]. 6 [erg·cm -3 It can also be made larger than ]. Next, by changing the second electrodeposition potential to -350 to -900 [mV vs. Ag / AgCl], which is different from the first electrodeposition potential, and performing electrodeposition, a second magnetic layer 32 with Co at 10 to 55 [at.%] can be formed on the surface of the first magnetic layer 31. The second magnetic layer 32 has a Co at 10 to 20 [at.%], resulting in a remanent magnetization of 100 [emu·cm]. -3 It is small, and the magnetic anisotropy constant Ku is 1 × 10⁻⁶. 5 [erg·cm -3 It can also be made smaller than ].

[0056] Thus, in the manufacturing method according to the second embodiment, the Co content is 45-55 [at.%] and the magnetic anisotropy constant Ku (>1 × 10) is large. 6 [erg·cm -3 On the first magnetic layer 31 made of a CoPt alloy having ]), Co is 10-20 [at.%] and has a small magnetic anisotropy constant Ku (<1 × 10 5 [erg·cm -3 A magnetic material 10 can be fabricated by stacking a second magnetic layer 32 made of a CoPt alloy having ]).

[0057] In the second embodiment, as in the first embodiment, the electrodeposition time and the thickness of the first magnetic layer 31 and the second magnetic layer 32 are proportional, and the thickness of the first magnetic layer 31 and the second magnetic layer 32 can be increased by increasing the electrodeposition time. By increasing the thickness of the first magnetic layer 31 and the second magnetic layer 32, the magnetization amount of the magnetic material 10 can be increased. In addition, by increasing the thickness of the first magnetic layer 31 and the second magnetic layer 32, the anisotropic magnetic field Hk, coercivity Hc, and nucleation magnetic field Hn in the magnetic material 10 can be reduced.

[0058] <AFM image of the surface of the magnetic material according to the second embodiment> Next, following the manufacturing method described above, the first magnetic layer 31 and the second magnetic layer 32 were actually fabricated by electrodeposition, and the surface roughness Ra of the second magnetic layer 32, which is the outermost surface, was measured by AFM. Here, a base was prepared by forming a 5 nm thick Ti film 4 on a Si substrate 5, and a Pt substrate 2 (Pt substrate) was fabricated on the surface of the Ti film 4 of the base by sputtering. The thickness of the Pt substrate was set to 15 nm.

[0059] The electrodeposition bath was prepared using 1 mM CoSO4, 1 mM H₂PtCl₆, and 0.1 M Na₂SO4. The bath concentration was reduced to decrease the deposition rate. In addition, to avoid inhibiting Pt nucleation, no additives such as ammonium citrate or glycine were added to the electrodeposition bath. A mesh-structured counter electrode made of Pt and a reference electrode made of Ag / AgCl were placed inside the electrolytic cell. The Pt substrate 2 was then immersed in the electrodeposition bath inside the electrolytic cell, and constant potential electrodeposition was performed at room temperature and pressure with a first electrodeposition potential of -650 mV (-650 mV vs. Ag / AgCl) relative to the reference electrode. The electrodeposition time was 75 s, and the first magnetic layer 31 was slowly deposited on the surface of the Pt substrate 2 in the electrodeposition bath. As a result, a first magnetic layer 31 made of CoPt alloy and with a thickness of 5 nm was formed on the Pt substrate 2.

[0060] Next, while the Pt substrate 2, on which the first magnetic layer 31 was formed on its surface, was immersed in the electrodeposition bath, the electrodeposition potential was changed to the second electrodeposition potential of -405 [mV] (-405 [mV vs. Ag / AgCl]) and constant potential electrodeposition was performed. The electrodeposition time was 300 [s], and the second magnetic layer 32 was slowly deposited on the surface of the first magnetic layer 31 in the electrodeposition bath. As a result, a second magnetic layer 32 made of a CoPt alloy with a thickness of 5 to 7 [nm] was formed on the first magnetic layer 31, and a magnetic material 10 was obtained in which the second magnetic layer 32 was laminated on the first magnetic layer 31. In the magnetic material 10, the electrodeposition potential for forming the second magnetic layer 32 was set to -405 [mV], which is higher than the electrodeposition potential for forming the first magnetic layer 31, and the Co content of the second magnetic layer 32 was reduced compared to the Co content of the first magnetic layer 31. Furthermore, the magnetic anisotropy constant Ku of the second magnetic layer 32 was made smaller than that of the first magnetic layer 31.

[0061] Then, when the surface of the second magnetic layer 32, which is the outermost surface of the obtained magnetic material 10, was observed using AFM, the AFM image shown in Figure 14 was confirmed. From Figure 14, it was confirmed that the surface of the second magnetic layer 32 had a roughness Ra of 1.4 [nm]. It was also confirmed that the outermost second magnetic layer 32 was formed smoothly with few irregularities. It was confirmed that the magnetic material 10 could be formed with thin first magnetic layer 31 and second magnetic layer 32, and that a smooth surface could be formed.

[0062] Next, the surfaces of the first magnetic layer 31 and the second magnetic layer 32 were observed by AFM, and the AFM images shown in Figures 15A and 15B were obtained. Figure 15A shows the AFM image of the surface of the first magnetic layer 31, and Figure 15B shows the AFM image of the surface of the second magnetic layer 32. For comparison, Figure 15C also shows the AFM image of the surface of the second magnetic layer 32 formed on the first magnetic layer 31 shown in Figure 14.

[0063] From 15A in Figure 15, it was confirmed that the surface roughness Ra of the first magnetic layer 31 alone is 0.43 [nm]. Also, from 15B in Figure 15, it was confirmed that the surface roughness Ra of the second magnetic layer 32 alone is 1.14 [nm]. It was confirmed that the surface of the first magnetic layer 31, which has a higher magnetic anisotropy constant Ku than the second magnetic layer 32, is formed smoothly. On the other hand, it was confirmed that the surface of the second magnetic layer 32, which has a lower magnetic anisotropy constant Ku than the first magnetic layer 31, is rougher than that of the first magnetic layer 31 because it has a lower Co content and a higher Pt content.

[0064] Furthermore, as can be seen from 15C in Figure 15, the outermost surface of the magnetic material 10, in which the second magnetic layer 32 is laminated on the first magnetic layer 31, has lower smoothness than the surface of the first magnetic layer 31 alone or the surface of the second magnetic layer 32 alone. Nevertheless, the roughness Ra is 1.43 [nm], indicating that it still possesses excellent smoothness.

[0065] <TEM image of a cross-section of a magnetic material according to the second embodiment> Next, when the cross-section of the magnetic material 10 created in the "AFM image of the surface of the magnetic material according to the second embodiment" described above was observed by TEM, a TEM image like the one shown in Figure 16, 16A was obtained. Figure 16, 16B is a TEM image of a magnified portion of 16A. Here, in order to clarify the surface contour of the second magnetic layer 32, a Ni coating 6 was formed on the surface of the second magnetic layer 32.

[0066] From 16A and 16B of Figure 16, it was confirmed that the magnetic material 10 has a two-layer structure consisting of a first magnetic layer 31 and a second magnetic layer 32. It was also confirmed that the first magnetic layer 31 of the magnetic material 10 is neatly stacked on the surface of the substrate 2 without any gaps. Similarly, it was confirmed that the second magnetic layer 32 is neatly stacked on the surface of the first magnetic layer 31 without any gaps. Furthermore, it was confirmed that both the first magnetic layer 31 and the second magnetic layer 32 appear to be deposited in a columnar shape perpendicular to the formation surface. It was confirmed that both the first magnetic layer 31 and the second magnetic layer 32 are oriented in an fcc structure.

[0067] <EDS mapping image of a cross-section of a magnetic material> Next, the cross-section of the magnetic material 10 created in the "AFM image of the surface of the magnetic material according to the second embodiment" described above was examined using EDS, and the results shown in Figures 17A to 17D were obtained. Figure 17A shows a TEM image of the cross-section of the magnetic material 10, and Figure 17B shows an EDS mapping image in which Co, Pt, Ti, Si, O, and Ni are mapped in correspondence with the magnetic material 10 in 17A. Figures 17C and 17D show EDS mapping images in which only Co and only Pt are mapped, respectively, in correspondence with the magnetic material 10 in 17A.

[0068] According to the EDS mapping images 17B-17D in Figure 17, the first magnetic layer 31 and the second magnetic layer 32 can be clearly seen in layers, confirming that it is a two-layer structure. Furthermore, it was found that Co and Pt are uniformly distributed in each layer at different concentrations and are mixed at the atomic level, confirming that the first magnetic layer 31 and the second magnetic layer 32 are uniform layers of CoPt alloy.

[0069] <Atomic resolution EDS image of a cross-section of a magnetic material according to the second embodiment> Next, when the cross-section of the magnetic material 10 created in the "AFM image of the surface of the magnetic material according to the second embodiment" described above was examined using an atomic-resolution EDS image, the results shown in Figures 18A and 18B were obtained. From Figure 18A, it was confirmed that the atoms of Pt in the substrate 2 and the atoms of the Co alloy in the first magnetic layer 31 are arranged in a regular pattern. It was also confirmed that the atoms of the Co alloy in the first magnetic layer 31 and the atoms of the Co alloy in the second magnetic layer 32 are arranged in a regular pattern. Figure 18B is an atomic-resolution EDS image showing Co and Pt in different colors, and it is possible to determine whether the atoms are Pt or Co from the color scheme. From Figure 18B, it was confirmed that in the first magnetic layer 31 and the second magnetic layer 32, the colors representing Co and Pt are uniformly mixed within the layers, respectively, and that Co atoms and Pt atoms are uniformly distributed within the layers. This also confirmed that the first magnetic layer 31 and the second magnetic layer 32 are formed from an alloy of Co and Pt.

[0070] <EDS mapping image and EDS compositional analysis results of the cross-section of the magnetic material according to the second embodiment> Next, EDS compositional analysis was performed on the cross-section of the magnetic material 10 created in the "<AFM image of the surface of the magnetic material according to the second embodiment>" described above, and the results shown in Figures 19A and 19B were obtained. Figure 19A shows the EDS mapping image of the cross-section of the magnetic material 10, and Figure 19B shows the EDS compositional analysis results, plotting the elemental composition in the region enclosed by the solid line in 19A, corresponding to each layer of the EDS mapping image. From Figures 19A and 19B, it can be seen that the composition of the first magnetic layer 31 (CoPt layer (thickness 5 [nm])) is Co 45 Pt 55 The composition of the second magnetic layer 32 (CoPt layer (thickness 7 [nm])) is Co 17 Pt 83 It was confirmed that this was the case.

[0071] <XRD measurement results of the magnetic material according to the second embodiment> Next, a magnetic material 10 having a first magnetic layer 31 and a second magnetic layer 32 with the composition shown in 20A of Figure 20 was manufactured according to the "<Method for Manufacturing a Magnetic Material According to the Second Embodiment>" described above, and the XRD was measured for the magnetic material 10. As shown in 20A of Figure 20, the magnetic material 10 is Co 45 Pt 55 A first magnetic layer 31 consisting of and having a thickness of 5 [nm] is formed on a substrate 2 made of Pt, Co 17 Pt 83 The configuration consists of a second magnetic layer 32 made of and having a thickness of 6 [nm], which is laminated on the first magnetic layer 31. In addition, separately, Co 45 Pt 55 A magnetic material (referred to as a first-layer monolayer film) is formed on a substrate 2, consisting of a first magnetic layer 31 with a thickness of 5 [nm], and Co 17 Pt 83 A magnetic material (referred to as a second single-layer film) was fabricated by forming only a second magnetic layer 32, which has a thickness of 6 nm, on the substrate 2.

[0072] Figure 20, section 20B shows the XRD measurement results of the magnetic material 10 shown in 20A, the XRD measurement results of the first single-layer film, and the XRD measurement results of the second single-layer film. According to Figure 20, section 20B, the magnetic material 10 shows not only an fcc CoPt(111) peak in the first magnetic layer 31, but also an fcc Pt(111) peak in the second magnetic layer 32, confirming that both the first magnetic layer 31 and the second magnetic layer 32 are stacked in an fcc structure. Furthermore, it was confirmed that the fcc Pt(111) peak of the second magnetic layer of the magnetic material 10 is shifted to a higher angle compared to the peak of the second single-layer film.

[0073] <Magnetic curve of the magnetic material according to the second embodiment> Next, the out-of-plane and in-plane magnetization curves were measured for the following configurations: one in which only the first magnetic layer 31 is provided (first layer single film), as shown in Figure 15A; one in which only the second magnetic layer 32 is provided (second layer single film), as shown in Figure 15B; and one in which the second magnetic layer 32 is laminated on the first magnetic layer 31, as shown in Figure 15C.

[0074] Figure 21, section 21A, shows the magnetization curve of the first single layer film. The magnetization curve of the first single layer film has a PMA loop, confirming that it exhibits magnetic anisotropy. The magnetization amount calculated from this magnetization curve is 3.1 × 10⁻⁶. -4 The coercivity Hc was 2.36 [KOe]. Figure 21B shows the magnetization curve of the second single layer film. The magnetization curve of the second single layer film has a PMA loop, confirming that it has magnetic anisotropy. The magnetization amount calculated from this magnetization curve is 1.2 × 10⁻⁶. -4 The coercivity was [emu] and the coercivity Hc was 0.34 [KOe]. Figure 21, 21C shows the magnetization curve of the magnetic material 10, in which a second magnetic layer 32 is stacked on a first magnetic layer 31. As shown in Figure 21, 21C, the magnetization curve of the magnetic material 10 has a PMA loop, confirming that it has magnetic anisotropy. The amount of magnetization calculated from this magnetization curve is 4.3 × 10⁻⁶. -4 The value was [emu], and the coercivity Hc was 1.72[KOe].

[0075] The saturation magnetization Ms of the magnetic material 10 shown in 21C of Figure 21 was found to be higher than the saturation magnetization Ms of the first single-layer film shown in 21A, and was found to be the sum of the saturation magnetization Ms of the first single-layer film shown in 21A and the saturation magnetization Ms of the second single-layer film shown in 21B. On the other hand, the coercivity Hc of the magnetic material 10 shown in 21C of Figure 21 was found to be lower than the coercivity Hc of the first single-layer film shown in 21A.

[0076] <Effects and Effects> As described above, the magnetic material 10 according to the second embodiment has a configuration in which a first magnetic layer 31 and a second magnetic layer 32 are laminated on a substrate 2, and both the first magnetic layer 31 and the second magnetic layer 32 have magnetic anisotropy and an fcc structure. Even with a magnetic material 10 having such a configuration, the first magnetic layer 31 and the second magnetic layer 32 can be formed by depositing them by electrolytic deposition, and can be manufactured at room temperature and pressure without using the sputtering method.

[0077] In the second embodiment, the magnetic anisotropy constants Ku of the first magnetic layer 31 and the second magnetic layer 32 can be freely changed simply by changing the electrodeposition potential using the electrodeposition method. Therefore, a magnetic material 10 having a first magnetic layer 31 and a second magnetic layer 32 with different magnetic anisotropy constants Ku can be easily manufactured. Furthermore, in the second embodiment, when forming the first magnetic layer 31 and the second magnetic layer 32, it is only necessary to change the electrodeposition potential while using the same electrodeposition bath, so it can be easily manufactured at room temperature and pressure.

[0078] <Other Embodiments> In the second embodiment described above, a magnetic material 10 was described in which a second magnetic layer 32 having a small magnetic anisotropy constant Ku is laminated on a first magnetic layer 31 having a large magnetic anisotropy constant Ku. However, the present invention is not limited to this. For example, as another magnetic material, a magnetic material may be provided in which a second magnetic layer having a large magnetic anisotropy constant Ku is laminated on a first magnetic layer having a small magnetic anisotropy constant Ku. Furthermore, as shown in Table 1 above, the magnetic anisotropy constant can also be changed by changing the thickness of the first magnetic layer 31 and the second magnetic layer 32. Therefore, the thickness of the first magnetic layer 31 and the second magnetic layer 32 can be changed to have different magnetic anisotropy constants Ku for the first magnetic layer 31 and the second magnetic layer 32.

[0079] Furthermore, although the second embodiment described above describes a two-layer magnetic material 10 in which a first magnetic layer 31 and a second magnetic layer 32 are stacked, the present invention is not limited to this, and may also be an N-layer magnetic material in which N layers (N is any natural number) of magnetic layers are stacked. For example, it may be a magnetic material with an N-layer structure in which a first magnetic layer with a large magnetic anisotropy constant Ku and a second magnetic layer with a smaller magnetic anisotropy constant Ku than the first magnetic layer are alternately stacked. Also, the magnetic anisotropy constant Ku may be changed for each of the N stacked magnetic layers, and it may be a magnetic material in which a plurality of magnetic layers having different magnetic anisotropy constants Ku are stacked in a regular order. In this case, the magnetic anisotropy is improved by the strain between each magnetic layer.

[0080] Furthermore, a magnetic material having multiple magnetic layers with different magnetic anisotropy constants Ku stacked together can be manufactured in the same way as in the second embodiment, by performing constant potential electrodeposition under the electrodeposition conditions shown in Figure 9, by appropriately switching the electrodeposition time and electrodeposition potential.

[0081] The magnetic material 10 according to the second embodiment can be used, for example, as the PIN layer of a perpendicular magnetization type MRAM (Magnetoresistive Random Access Memory) or as the PIN layer of a TMR sensor. Furthermore, the magnetic material 10 according to the second embodiment has an fcc structure and magnetic anisotropy, and can be provided with a first magnetic layer 31 and a second magnetic layer 32 with smoothly formed surfaces, resulting in a structure that facilitates the flow of spin-polarized current, and can therefore be applied, for example, to the PIN layer of a perpendicular magnetization type MRAM (STT-MRAM) or a TMR sensor.

[0082] Furthermore, while the second embodiment described a magnetic material 10 in which a second magnetic layer 32 is formed directly on the surface of a first magnetic layer 31, the present invention is not limited thereto. For example, other magnetic materials may include a magnetic material in which an intermediate layer is provided between the first magnetic layer 31 and the second magnetic layer 32. Also, in a magnetic material in which magnetic layers are stacked in N layers, an intermediate layer may be provided between each magnetic layer. In such a magnetic material, the magnetic interaction can be changed by the intermediate layer. [Explanation of Symbols]

[0083] 1, 10 Magnetic material 2 circuit boards 3 magnetic layer 31. First magnetic layer (magnetic layer) 32. Second magnetic layer (magnetic layer)

Claims

1. A magnetic material containing a magnetic layer, The magnetic layer is a magnetic material having magnetic anisotropy and an fcc structure.

2. The magnetic material according to claim 1, wherein the magnetic layer is a Co alloy containing at least one of Pt, Au, Pd, and Cu.

3. The magnetic material according to claim 1, wherein the magnetic layer has a surface roughness Ra of 2 [nm] or less.

4. The magnetic material according to claim 2, wherein the magnetic layer has a Co content of 10 to 55 [at. %].

5. The magnetic layer has a magnetic anisotropy constant of 1 × 10⁻⁶ ６ [erg・cm －３ A magnetic material according to claim 4, which is larger than ].

6. The magnetic layer has a magnetic anisotropy constant of 1 × 10⁻⁶ ５ [erg・cm －３ A magnetic material according to claim 4, which is smaller than ].

7. The magnetic material according to claim 1, wherein the magnetic layer has a thickness of 10 nm or less.

8. Furthermore, including a substrate, The magnetic material according to claim 1, wherein the difference between the lattice constant of the substrate and the lattice constant of the magnetic layer is 10% or less of the lattice constant of the substrate.

9. A magnetic material having a first magnetic layer and a second magnetic layer laminated together, Both the first magnetic layer and the second magnetic layer have magnetic anisotropy and an fcc structure. magnetic material.

10. The magnetic material according to claim 9, wherein the magnetic anisotropy constant of the first magnetic layer is greater than the magnetic anisotropy constant of the second magnetic layer, or the magnetic anisotropy constant of the first magnetic layer is smaller than the magnetic anisotropy constant of the second magnetic layer.

11. The magnetic material according to claim 10, wherein the first magnetic layer and the second magnetic layer are alternately stacked.

12. The magnetic material according to any one of claims 9 to 11, further comprising an intermediate layer between the first magnetic layer and the second magnetic layer for changing the magnetic interaction.

Images