Journal of the Magnetics Society of Japan
Online ISSN : 1882-2932
Print ISSN : 1882-2924
ISSN-L : 1882-2924
36 巻, 3 号
選択された号の論文の27件中1~27を表示しています
磁気記録
  • 川前 武士, 小峰 啓史, 杉田 龍二
    2012 年 36 巻 3 号 p. 141-144
    発行日: 2012/05/01
    公開日: 2012/05/18
    ジャーナル オープンアクセス
      Magnetic printing characteristics along the cross-track direction on ECC media were investigated by using micromagnetic simulation. There is an optimum printing field in which the difference between ideal and calculated magnetization distributions is minimum except for checker patterns in edge printing. It was clarified that the difference in bit printing was smaller than that in edge printing. When the bit size becomes smaller, the ratio of the difference to the track pitch became larger. The difference in dot patterns was smaller than that in checker patterns for bit printing, whereas the difference in checker patterns was smaller than that in dot patterns for edge printing.
  • 山口 義明, 川田 裕介, 小峰 啓史, 杉田 龍二
    2012 年 36 巻 3 号 p. 145-149
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/24
    ジャーナル オープンアクセス
      The effect of applied magnetic field direction on the magnetic cluster size of exchange coupled composite (ECC) media was analyzed by using micromagnetic simulation. The magnetization distribution in all cases exhibited a maze domain structure. The magnetic cluster size decreased as the applied field direction tilted from perpendicular to in-plane. For the hard layer only and the soft layer only, the magnetic cluster size in the perpendicular applied field was the same as that in the in-plane field. The soft layer dominated the magnetic cluster size of the ECC medium in the perpendicular field, whereas the hard layer dominated that in the in-plane field.
  • 高橋 達明, 朝香 壮太, 吉田 和悦, 金井 靖
    2012 年 36 巻 3 号 p. 150-154
    発行日: 2012/05/01
    公開日: 2012/05/18
    ジャーナル オープンアクセス
      Microwave-assisted magnetic recording (MAMR) has been proposed as a promising technique to achieve a higher areal recording density over 1.0 Tbit/inch2. MAMR requires a spin-torque oscillator (STO) to generate a strong, high-frequency magnetic field to induce magnetic resonance in a recording medium. The oscillation properties of STOs were previously investigated using micromagnetic models. However, simple models were used that neglected the magnetic interactions between the STO and a single-pole-type (SPT) recording head. The interactions and the magnetic field in the gap between the main pole and the trailing shield might strongly affect the oscillating characteristics. Thus, a new simulator that combines an SPT head and an STO simulator, called an integrated MAMR simulator, has been developed. The magnetic interactions between an SPT and an STO are revealed to have considerable effects on the oscillating frequency and the field strength.
  • B. Rezaeealam, T. Ueno, S. Yamada
    2012 年 36 巻 3 号 p. 155-160
    発行日: 2012/05/01
    公開日: 2012/05/18
    ジャーナル オープンアクセス
      The paper aims at the behaviour analysis of the Galfenol rods under bending conditions that are employed in a vibration energy harvester by illustrating the spatial variations in stress and magnetic field. Armstrong model is employed to predict the magnetization and magnetostriction as a function of stress and magnetic field and it is incorporated into a static finite element model of vibration-driven generator by which the compressive and tensile stresses contributions to change in magnetic flux densities in the Galfenol rods were calculated and the effectiveness of the inspected vibration-driven generator in voltage generation and energy harvesting is demonstrated.
磁気物理
  • 小畑 修二
    2012 年 36 巻 3 号 p. 161-168
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/10
    ジャーナル オープンアクセス
      The use of hyperthermia as a cancer therapy has become an important form of treatment along with radiation and chemotherapy. Magnetic-induction hyperthermia was developed about fifty years ago, and has evolved into new techniques based on recently developed nano-materials. Implant heating systems (IHS) have also evolved due to the use of nano-particles and grains of ferrites, iron, and magnetic alloys. Induction heating systems have two thermo-mechanisms of eddy currents and B-H hysteresis losses. Induction heating characteristics of thermo-mechanisms in these nanoscale materials were investigated for their use in controlling the hyperthermia temperature. The retarded trace method was introduced as a means of investigating hysteresis characteristics.
  • 池原 成拓, 和田 翔, 小林 司, 後藤 聡希, 吉田 和彦, 石橋 隆幸, 西 敬生
    2012 年 36 巻 3 号 p. 169-172
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/10
    ジャーナル オープンアクセス
      Polycrystalline Bi3Fe5O12/BiY2Fe5O12 magneto-optical thin films were prepared by using a metal-organic decomposition (MOD) method on glass substrates. This was achieved by using YIG buffer layers, that is, BiY2Fe5O12 films, which allow bismuth and iron oxides to take a garnet structure. The samples were characterized by X-ray Diffraction (XRD) and magneto-optical spectroscopy. The Faraday rotation of the BIG/Bi-YIG films was 13.55 deg/μm at a wavelength of 525 nm, and a maximum figure of merit of the BIG/Bi-YIG films was obtained at 528 nm. In addition, the well-matched lattice constant of BIG with the relationship between the lattice constant and the Bi-substitution rate was shown by successful crystallization of BIG.
  • 佐藤 知徳, 仲谷 栄伸
    2012 年 36 巻 3 号 p. 173-178
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/24
    ジャーナル オープンアクセス
      The stability of the vortex structure on vortex core switching was investigated by using micromagnetic simulation. The method by the vortex core switching simulation by AC spin current is used to investigate this. Furthermore, the adequacy of the result was investigated by the evaluation of the magnetic energy. The switching simulation revealed that the vortex core did not switch around the transition dimension of magnetic disks between single-domain structure and the vortex structure in a remanent state, and the disk diameter needed to be increased to about 20 to 80 nm for stable vortex core switching compared with the stability limit in the remanent state. Furthermore, the results we obtained from our evaluation of magnetic energy agreed with the results obtained by simulating vortex core switching. Therefore, the result of the core switching simulation is also assured by the evaluation of magnetic energy.
薄膜,微粒子,多層膜,人工格子
  • 杉本 望実, 深谷 直人, 吉原 健彦, 宮脇 哲也, 植田 研二, 田中 信夫, 浅野 秀文
    2012 年 36 巻 3 号 p. 179-182
    発行日: 2012/05/01
    公開日: 2012/05/18
    ジャーナル オープンアクセス
      Half-Heusler La-Pt-Bi thin films were prepared by 3-source magnetron sputtering on various single crystal substrates. Single phase, c-axis oriented La-Pt-Bi thin films were successfully obtained on YAlO3(001) substrate. Formation of secondary phases was effectively prevented by precise control of the deposition rate for separate targets, as well as adjustment of the deposition temperature. The crystallinity of LaPtBi thin films is improved by the reduction of lattice mismatch between LaPtBi and substrates. Electrical resistivity of La-Pt-Bi thin films increases with decreasing (increasing) La (Bi) contents. From X-ray photoelectron spectroscopy, double peaks were observed in La 3d orbital. This result suggest the co-existence of orbital with and without charge transfer, which may affect the the electrical properties of La-Pt-Bi thin films. Control of the electronic structure of La is one of the key to improve the electrical property of LaPtBi.
  • 鈴木 祐太, 後藤 太一, 江藤 優, 高木 宏幸, Pang Boey Lim, Alexander V. Baryshev, 井上 光輝
    2012 年 36 巻 3 号 p. 183-187
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/24
    ジャーナル オープンアクセス
      One of realization of magnetophotonic crystals (MPCs) has a microcavity structure where a thin magnetic garnet film-bismuth-substituted yttrium iron garnet (Bi:YIG)-is sandwiched between two Bragg mirrors (BMs) made of Ta2O5 and SiO2. For MPCs fabricated by sputtering, annealing of as-sputtered Bi:YIG films is essential for garnet crystallization. However, Ta2O5 is also crystalized at garnet crystallization temperatures, when utilizing a conventional annealing in an electric furnace. Ta2O5 crystallization worsens optical parameters of BMs and consequently properties of an MPC. To overcome this problem, we selectively annealed as-sputtered Bi:YIG/BM samples by a high power laser. Experiments showed that Bi:YIG can be crystallized while keeping Ta2O5 in the amorphous state; this was confirmed by the transmission electron microscopy.
  • 田代 裕樹, 宮脇 哲也, 植田 研二, 浅野 秀文
    2012 年 36 巻 3 号 p. 188-191
    発行日: 2012/05/01
    公開日: 2012/05/18
    ジャーナル オープンアクセス
      Mn3GaN thin films were grown on MgO and SrTiO3 substrates by ion beam sputtering, and their structural and electric properties have been investigated. Control of growth temperature is important to obtain single phase Mn3GaN thin films. Resistivity of Mn3GaN thin film increase with increasing temperature and reach a maximum at 286 K-297 K. The maximum resistivity is attributed to the magnetic transition from antiferromagnetism to paramagnetism. On SrTiO3 substrates which have 0.2% lattice mismatch to Mn3GaN, single crystal Mn3GaN thin films were grown.
  • 川田 裕介, 小野瀬 勝, 川崎 龍太, 大山 哲広, 小峰 啓史, 杉田 龍二
    2012 年 36 巻 3 号 p. 192-196
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/24
    ジャーナル オープンアクセス
      The relation between thickness and magnetic properties of CoPt perpendicular magnetic anisotropy film was investigated through experiments and micromagnetic simulation. The perpendicular nucleation field and saturation field decreased as the film thickness decreased, whereas the in-plane squareness ratio increased as the thickness decreased. The increase in in-plane squareness ratio with decreasing thickness was due to an expansion of the domain wall region that occurred with the decrease in thickness.
  • 後藤 太一, 橋本 良介, 磯谷 亮介, 鈴木 祐太, 荒木 隆平, 高木 宏幸, 井上 光輝
    2012 年 36 巻 3 号 p. 197-201
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/24
    ジャーナル オープンアクセス
      We fabricated a microcavity -a magneto-optical (MO) film and an electro-optical (EO) film are sandwiched between two Bragg mirrors (BMs)- for development of magneto-optical spatial light modulators driven by electric field (e-MOSLMs). We used (Bi0.5Dy0.7Y1.8)3(Fe3.3Al1.7)5O12 as a MO film and (Pb91La9)1(Zr65Ti35)1O3 (PLZT) as an EO film. The samples showed enhanced Faraday rotation loops and electrical polarization loops, simultaneously. The X-ray diffraction patterns, MO and EO characteristics were measured. Experimental results showed that EO and MO films were successfully formed between BMs.
  • 小川 智之, 藏 裕彰, 高橋 研
    2012 年 36 巻 3 号 p. 202-208
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/10
    ジャーナル オープンアクセス
      Two different approaches to obtain monodisperse Fe nanoparticles (NPs) in a wide range of average diameters based on thermal decomposition of Fe(CO)5 were developed; the first is thermal decomposition of a Fe(CO)5-oleylamine (OAm) reacted precursor, and the second is a method of Fe(CO)5 slow injection. OAm as a surfactant strongly adsorbed on an Fe atom in the thermal decomposition of a Fe(CO)5-OAm reacted precursor and restricted the particle growth process. As a result, small NPs 2.3 nm in diameter were obtained. Moreover, it was possible to control the NP diameter in the range from 2.3 to 10 nm by changing the reaction temperature and the time for precursor preparation. However, large NPs over 20 nm in diameter were obtained with the method of slow injection by promoting the process of particle growth. Controls for the density of dissolved Fe atoms and Fe NPs in a reaction solution were required to accelerate particle growth without nucleation. Modifications to the injection rate and/or thermal decomposition temperature of Fe(CO)5 thus enabled us to control the NP diameter in the range from 12 to 21 nm.
  • 小林 伸聖, 鶴井 隆雄, 石田 今朝男, 岩佐 忠義, 荒井 賢一, 増本 健
    2012 年 36 巻 3 号 p. 209-212
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/24
    ジャーナル オープンアクセス
      We have investigated the thermal change of the structure of FeCo-MgF nano-granular TMR films used for high sensitivity magnetic sensor GIGS. As a result, the grain size of MgF2 crystals that form intergranule increases with increasing of heating temperature, and it is thought that electric resistivity of these films increases by this structural change. Furthermore, FeCo granules grow and joins together partially over 543K. Films magnetism changes from super paramagnetism to ferromagnetism with this structural change. It is thought that magnetic change is the reason MR ratio decreases.
スピンエレクトロニクス
  • 小林 耕平, 深谷 直人, 宮脇 哲也, 植田 研二, 浅野 秀文
    2012 年 36 巻 3 号 p. 213-216
    発行日: 2012/05/01
    公開日: 2012/05/18
    ジャーナル オープンアクセス
      Layered structures composed of ferromagnetic, half-metallic Heusler Fe2CrSi (FCS) and ferroelectric perovskite Ba0.7Sr0.3TiO3 (BSTO) have been grown on LaAlO3 (001) (LAO) substrates by magnetron sputtering. Their magnetic and ferroelectric properties have been investigated. BSTO/FCS bilayer structures are epitaxially grown on LaAlO3 substrates with BSTO (001)[100]//FCS (001)[110] relationship. The remanent polarization of 40 μC/cm2 was observed at RT in a single-layer BSTO thin film. The layered structure exhibited saturation magnetization of 400 emu/cc at RT, which is equivalent to the bulk one. Therefore, the BSTO/FCS epitaxial heterostructure is a promising candidate for fabricating multiferroic devices.
  • 藤 慶彦, 原 通子, 湯浅 裕美, 福澤 英明
    2012 年 36 巻 3 号 p. 217-222
    発行日: 2012/05/01
    公開日: 2012/05/18
    ジャーナル オープンアクセス
      We have investigated a new magnetic material composed of ultra-thin oxide spin-filtering layer (SFL)/ferromagnetic layer (FML) for magnetoresistance (MR) enhancement. By inserting Zn-Fe oxide as a SFL material in current-perpendicular-to-plane giant magnetoresistive (CPP-GMR) films, the MR ratio and ΔRA (the change of resistance area product) were enhanced to 26.0% and 52 mΩμm2 at a small RA (resistance area product) of about 0.2 mΩμm2, respectively. Structural analysis revealed that the Zn wüstite structure is responsible for the enhancement of the MR ratio, and wüstite/FML structure has higher spin-polarization than that for spinel ferrite/FML. Although wüstite has not been predicted to be high spin-polarization material and little experimental data on the transport property has been reported, our results indicate that wüstite has potential as high spin-polarization material for future spin electronics.
  • 大庭 綾香, 藤村 勇馬, 小峰 啓史, 杉田 龍二
    2012 年 36 巻 3 号 p. 223-228
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/24
    ジャーナル オープンアクセス
      The effect of pinning sites that originated from magnetic anisotropy distributions on critical current velocity in current-induced domain wall motion was investigated by using micromagnetic simulation. As a result, we found the pinning position and size had almost no effect on the critical current velocity. Moreover, the decrease in saturation magnetization reduced the critical current density even if the nanowire had pinning sites that originated from the anisotropy distribution. Since the estimated pinning field was attributed to the intermediate pinning region, the magnetic anisotropy distribution had almost no effect on the critical current density.
計測,高周波デバイス
パワーマグネティックス
  • 長谷川 祐, 中村 健二, 一ノ倉 理
    2012 年 36 巻 3 号 p. 245-248
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/10
    ジャーナル オープンアクセス
      The switched reluctance (SR) motor is low cost, extremely robust, and has a wide range of variable speeds. However, its power density is generally inferior in comparison with conventional permanent magnet (PM) motors. This paper presents a novel SR motor that has auxiliary windings and permanent magnets in the stator yoke. It operates similarly to a conventional SR motor in the motoring mode. On the contrary, it operates as a permanent magnet reluctance generator (PMRG) in the generating mode. The basic characteristics of the proposed SR apparatus operating as a motor and generator were calculated by using the finite element method (FEM), and compared with those of conventional reluctance machines.
  • 佐藤 文博, 守田 淳, 田倉 哲也, 佐藤 忠邦, 松木 英敏
    2012 年 36 巻 3 号 p. 249-252
    発行日: 2012/05/01
    公開日: 2012/05/18
    ジャーナル オープンアクセス
      Electric vehicle (EVs) have been attracting a lot of attention as part of the proactive approach to global environment problems being taken around the world. However, existing EV batteries have not yet achieved high enough energy density of and thsu, EVs are not very common. The construction of the EV charging infrastructure is a key factor in solving this problem. Our objective is to construct charging system for a contactless power station for moving EVs, focusing on of safe handling of the high-power equipment and reducing the stop time required for charging. The electric power needed to operate this system is transmitted from the power transmission coil, which is located on the road, to receiving coil, which is installed on the underside of the EV. We designed and constructed a one-fifth of an actual vehicle scale model coil, and we used it to investigate the coupling factor and efficiency between coils when the gap between the power transmission coil and a receiving coil was changed.
  • 長尾 真理子, 中村 健二, 大日向 敬, 有松 健司, 坂本 邦夫, 一ノ倉 理
    2012 年 36 巻 3 号 p. 253-257
    発行日: 2012/05/01
    公開日: 2012/05/18
    ジャーナル オープンアクセス
      Variable inductors, which are composed of only a magnetic core and primary dc and secondary ac windings, can control the effective inductance of the secondary ac winding linearly and continuously by the primary dc current due to the effect of magnetic saturation. Variable inductors have advantageous features such as having a simple, and robust structure, and high reliability. Therefore, they can be applied as var compensators in electric power systems. A 6-leg three-phase laminated-core variable inductor was proposed in a previous paper. It had only one laminated-core in which three-phase secondary ac windings were installed, to reduce its size and weight in comparison with conventional single-phase variable inductors. A 18-leg three-phase-laminated-core variable inductor is proposed in this paper to further reduce size and weight. The basic characteristics of the proposed variable inductor were calculated based on reluctance network analysis (RNA).
  • 佐藤 宏樹, 後藤 博樹, 一ノ倉 理
    2012 年 36 巻 3 号 p. 258-262
    発行日: 2012/05/01
    公開日: 2012/05/18
    ジャーナル オープンアクセス
      Electric vehicles have recently attracted attention as future generation cars. It is especially important to have electrically driven heavy vehicles such as buses and trailers that have little environmental influence. Switched reluctance (SR) motors have no magnets. This means they have no thermal demagnetization, are inexpensive to manufacture, and have excellent mechanical strength. These advantages are suitable for application to the In-Wheel SR motors of electric vehicles. We developed in-wheel SR motors for heavy vehicles and carried out a proof load test on them.
  • 冨樫 知誠, 太田 裕也, 宮澤 正樹, 斎藤 修, 鶴本 勝夫
    2012 年 36 巻 3 号 p. 263-267
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/10
    ジャーナル オープンアクセス
      We have been reported on the various magnetic gears. Magnetic gears have many performance characteristics, for example, perfective non-contact, silent, oil les and maintenance free. Recently, we have been developed the magnetic planetary and differential gear. The gearings are would be effective for wind power generators. For the reason, we think that the gear system is able to maintain output sped of sun gear at constant by differential operating outer ring gear in spite of random input sped of planetary gear. In this report, it is described the test of output sped stability control using the magnet planetary gears with the functional 2 inputs. As the result, it was clarified it was possible to get the stable output sped with this unit.
生体磁気,医療応用
  • 加藤 健太郎, 岩崎 圭祐, 降矢 健太郎, 田村 直樹, 佐藤 忠邦, 田倉 哲也, 佐藤 文博, 松木 英敏
    2012 年 36 巻 3 号 p. 268-271
    発行日: 2012/05/01
    公開日: 2012/05/18
    ジャーナル オープンアクセス
      Functional electrical stimulation (FES) is a therapy used to rehabilitate patients with lost movement functions, and to apply stimulations. We adapted a method of implanted direct feeding method to apply stimulation as part of this therapy. Stimulus energy and signals for controlling devices are applied to devices by utilizing a mounted system using magnetic coupling. Power feeding is presently carried out with a serial resonance circuit in the method of direct feeding. Two feeding coils are used for the upper and lower arms individually in order not to disturb the movement in the joint of the elbow. Declination of resonance from variations in coupling interference from the movement of feeding coils is a problem. To solve it, we used a method that reduced variations in coupling interference by using a short coil between feeding coils. We report here the result of experiments conducted on this method.
  • 照澤 良祐, 小林 宏一郎, 吉澤 正人, 内川 義則
    2012 年 36 巻 3 号 p. 272-276
    発行日: 2012/05/01
    公開日: 2012/05/18
    [早期公開] 公開日: 2012/04/10
    ジャーナル オープンアクセス
      We studied signal source estimation of heart activity with magnetocardiograms (MCGs). Signal source estimation by standardized low resolution brain electromagnetic tomography (sLORETA) has recently been used in visualizing brain activity. sLORETA is a spatial filter method, that is suitable for estimating the spread signal source. However, sLORETA differs in its spread of the estimated solution due to the depth of the signal source. We propose a new method of reconstructing the estimated solution using sLORETA. Our results indicated that it was possible to reduce the difference in spread of estimated solutions that occurred due to depth. This paper explains the method we used to reconstruct the estimated solution and its effectiveness.
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