著者

山崎 慶太 奥田 清明 阿部 隆之 内川 義則 志村 徹 小谷 誠

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.16, no.6, pp.769-774, 1992-12-01 (Released:2013-01-11)

参考文献数

7

被引用文献数

6 7

---

This paper describes the design and the development of a prefabricated magnetically-shielded-room (PMSR) of the hexagonal type for high sensitive measurement of neuro-magnetic fields such as magnetoencephalography (MEG) mainly using SQUIDs with first and/or second-order gradiometers. This PMSR consists of prefabricated plywood panels 1.2 m wide×2.4 m high×24 mm thick. It covers a floor area of about 9 m2. The panel is sandwiched by two layers of high-μ metal sheets 1 mm thick. The shielding factor at the center of PMSR against the external magnetic field is 20 to 40 dB in the range of DC to 120 Hz. Magnetic noise inside PMSR measured by a second-order gradiometer was less than hundreds fT above 0.5 Hz excepting 50 Hz. In this case, a second order gradiometer was able to eliminate the common mode magnetic noise of about 20 Hz, which was essentially observed by a magnetometer, caused by the vibration of PMSR. These results were discussed and compared with the calculations.

著者

能登路 淳 菊川 亮一 藤井 直樹 早川 元造 斉藤 皓彦

出版者

The Magnetics Society of Japan

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.22, no.4, pp.657-660, 1998-04-15

参考文献数

6

被引用文献数

2 2

---

The effects of tensile stress and strain on magnetization and magnetic domains in grain-oriented silicon steel sheets were investigated. The strain-magnetization properties of plastic deformation regions under stress showed peculiar characteristics. The magnetization increased with decreasing strain and, after reaching a peak value, decreased with decreasing strain. We observed Lancet domains in a sample after removing stress applied to a plastic deformation region. This phenomenon can be explained by changes in the domain structures, which were partly observed. The results obtained in this investigation can be applied to the nondestructive detection of fatigue in metallic magnetic materials.

著者

木原 隆幸 小野 寛太 奥田 太一 原沢 あゆみ 尾嶋 正治 横尾 篤 木下 豊彦

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.25, no.4_2, pp.1059-1062, 2001 (Released:2007-02-02)

参考文献数

11

被引用文献数

2 3

---

The magnetic properties of thin films with reduced lateral dimension are significantly different from those of materials in the bulk state, and have provided a wealth of scientific interest and potential technological applications. It is therefore very important to study magnetism in microstructures or small magnetic domains, and one of the most powerful tools for investigating such magnetism is the photoelectron emission microscope with synchrotron radiation as its light source (SR-PEEM).We report in this paper our set-up of a new SR-PEEM system, and present the preliminary results.

著者

千田 正勝 武井 弘次 石井 修 越本 泰弘 戸島 知之

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.19, no.2, pp.465-468, 1995-04-01 (Released:2007-11-07)

参考文献数

13

被引用文献数

4 4

---

This study reports on the performance of a thin-film magnetic sensor that uses impedance change at a high frequency. A closed magnetic circuit, a strip pattern for the magnetic films, and an NiFe/SiO2 multilayer film structure were adopted for high sensitivity and large voltage change. A voltage change ratio of 50-60% was achieved by applying an external field of several Oe with an AC carrier of ∼800 MHz. The sensor was confirmed to perceive a highfrequency external field as an amplitude modulation of the AC carrier voltage, and exhibited broad frequency bandwidth, high linearity, and no hysteresis or Barkhausen noise.

著者

小澤 哲也 馬渡 宏 薮上 信 石山 和志 荒井 賢一

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.29, no.8, pp.831-837, 2005 (Released:2007-05-10)

参考文献数

5

被引用文献数

2 2

---

The impedance and phase characteristic of a magnetic thin film changes when a magnetic field is applied. The high-frequency-carrier magnetic field sensor, also called a GMI sensor, employs this phenomenon as its principle. We directed our attention to the change in the phase characteristic, and measured the dc magnetic field by measuring the phase as a phase difference, using the dual-mixer time-difference method. We optimized the method and the continuous sampling condition to measure the phase difference, and developed an efficient system for measuring the continuous sampling phase difference with low noise. The system was successfully used to measure the ac magnetic field by continuous sampling of the phase difference of a high-frequency-carrier magnetic field sensor.

著者

Giles Roscoe C. Mansuripur Masud

出版者

社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.17, no.1, pp.S1_255-257, 1993

被引用文献数

1

---

Computer simulations of a two-dimensional lattice of magnetic dipoles are performed on the massively parallel Connection Machine Supercomputer. These lattices constitute a discrete model for thin films of amorphous rare earth-transition metal (RE-TM) alloys, used in erasable optical data storage systems. The simulated dipoles follow the dynamic equation of Landau-Lifshitz-Gilbert. Using mean-field theory, we have calculated the temperature dependence of the subnetwork magnetizations, the effective fields, the gyromagnetic coefficient, and the Gilbert damping parameter. These results are then used in the simulation of the thermomagnetic recording process, where a focused laser beam creates a hot spot and allows an external magnetic field to reverse the direction of local magnetization. Reversed domains are seen to nucleate during cooling of a heated spot with Gaussian spatial profile. In the absence of defects of the size of a domain wall, these nuclei are seen to collapse in low external fields. In contrast, samples with patches of uniform anisotropy and weakened inter-patch exchange form stable reversed domains. Color visualizations of the magnetization distribution show local pinning of the cooling reverse domain on patch boundaries.

著者

片根 保

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.22, no.4_2, pp.789-791, 1998 (Released:2007-06-29)

参考文献数

12

---

The effects of dc magnetic fields on animals and plants have been studied for a long time. In particular, many studies of the effects on plants have been reported, because of the ease with which experiments can be controlled. However, it is still not clear whether dc magnetic fields have any influence on plants. This study shows the effects of both horizontal and vertical dc magnetic fields on the growth of Japanese radishes. A dc magnetic field plays a role in restricting the initial growth of radishes, and the growth and root hair are also affected by the direction of the magnetic field.

著者

中村 基訓 木村 道哉 末岡 和久 武笠 幸一

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.24, no.4_2, pp.771-774, 2000 (Released:2007-02-26)

参考文献数

14

被引用文献数

2 2

---

A variety of techniques have been proposed to measure surface magnetic properties using scanning probe microscopy. The most widely used is magnetic force microscopy (MFM). In many cases, however, it is hard to analyze MFM data quantitatively. A magnetoresistive (MR) device is also a candidate for such a sensor that can operate at room temperature with high sensitivity. Yamamoto et al. have demonstrated a scanning magnetoresistance microscope (SMRM) using a commercially available MR read-head for a hard disk. Since they held the MR head on a slider, there was no feedback system to control the distance between sample and sensor. We made a cantilever for the MR sensor to get the surface topography and magnetic properties simultaneously. Its magnetic field sensitivity with 10-mA sensing current is 90 μV/Oe, and our roughly estimated minimum field resolution is a few mOe (only Johnson noise is assumed with 10-kHz bandwidth at room temperature), which is much better than that of a scanning Hall probe microscope.

著者

内山 剛 牧野 正義 毛利 佳年雄

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.16, no.3, pp.556-559, 1992-06-01 (Released:2013-01-11)

参考文献数

3

被引用文献数

2 2

---

A transistor logic memory module based on the Royer oscillator type magnetic multivibrator is presented, in which a HTcSC thin disk core having six coils tightly set around it is connected with two switching transistors. The oscillation of this module is initiated by applying a pulse current to a coil and the phase of oscillation is controlled by the sign of the trigger pulse. That is, this module is a phase memory type logic device such as Parametron. Moreover, oscillation is terminated by applying a pulse current to a small transistor which shorts another coil of the HTcSC. We can assign two oscillating states with different phases to the numerical values ±1 and the non-oscillating state to 0. This logic is decided by a majority of multi-input, so that this module has applications in the field of neural network system.

著者

Choe Sug-Bong Shin Sung-Chul

出版者

公益社団法人日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:18804004)

巻号頁・発行日

vol.25, no.3, pp.180-185, 2001-03-15

被引用文献数

2

---

A magneto-optical microscope magnetometer (MOMM) has been developed to grab the domain reversal patterns in real time under applying a magnetic field, as well as, to simultaneously measure the local magnetic ptoperties with 400-nm spatial resolution.Using the system, the domain reversal behavior is revealed to change contrastingly between wall-motion and nucleation dominant with changing the multilayer structure of Co/Pd multilayers.From a quantitative analysis, the reversal ratio of the wall-motion speed over the nucleation rate is a governing parameter for the contrasting domain reversal dynamics.The activation volumes of the wall-motion and nucleation processes are found to be unequal, and the difference is closely ralated with the domain dynamics.Based on a Monte-Carlo simulation, both the macroscopic magnetic properties and the local magnetic variation are responsible for the contrasting domain reversal behavior.

著者

澤田 進

出版者

公益社団法人日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:18804004)

巻号頁・発行日

vol.29, no.4, pp.371-372, 2005-04-01

著者

増田 正美

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.3, no.3, pp.81-88, 1979-08-31 (Released:2010-05-18)

参考文献数

7

著者

三浦 健司 村岡 裕明 杉田 愃 中村 慶久

出版者

公益社団法人日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:18804004)

巻号頁・発行日

vol.24, no.4, pp.231-234, 2000-04-15

被引用文献数

38 34

---

In perpendicular magnetic recording, medium noise is one of the crucial issues limiting the attainable density. The purpose of the reported work was to find a guiding principle for reducing the medium noise. Although previous work suggested that the media noise is caused by reversed domains in the bit cell, our time-domain noise measurements and a novel model using Voronoi cells suggest another noise origin : a noise source of transition irregularity caused by finite magnetic cluster size.

著者

池添 泰弘 茂木 邦雄 鈴木 隆史 廣田 憲之 植竹 宏往 渋谷 正徳 中川 準 北沢 宏一

出版者

公益社団法人日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:18804004)

巻号頁・発行日

vol.23, no.4, pp.1557-1560, 1999-04-15

---

We succeeded in making water levitate in air, using not an extreme by strong magnet such as a Bitter-type hybrid matnet, but a compact superconducting magnet. The levitated water ball had a spherical shape and levitated stably for over a day. We named this phenomenon "magneto-Archimedes levitation," because, to achieve it, we used gravitational and magnetic buoyancy forces in the presence of pressurized oxygen gas. In additon, our method enables paramagnetic substances to levitate in air, which has been considered to be impossible owing to the Maxwell relation, divB=0. We also succeeded in making paramagnetic aqueous copper sulfate levitate in air. To the best of our knowledge, this is the first demonstration of stable levitation of paramagnetic substances in the atmosphere.

著者

小塚 洋司

出版者

公益社団法人日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:18804004)

巻号頁・発行日

vol.28, no.11, pp.1096-1102, 2004-11-01

参考文献数

13

被引用文献数

3

---

-色即是空.空即是色.-629年,秋八月,唐の玄奘三蔵は,長安を発ち仏法を求めて天竺(インド)に赴く.空に飛ぶ鳥なく,地に走獣,水草もなし.熱砂のタクラマカン砂漠を徒行し,氷雪春夏にも解けずといわれる標高七千メートルに迫る天山山脈を踏破して,天竺に至る苦行は想像を絶するものであったという.玄奘三蔵ときに29歳であった.16年の歳月を経て長安に戻った玄奘は,般若心経をインド語の原典から中国語に翻訳する.上記はその一仏説である.さて,磁性電波吸収体の主材料であるフェライトは,加藤与五郎,武井武雨博士によって,我が国で発明された誇るべき電気電子材料である.銅一亜鉛系のソフトフェライトが初めて作製されたのは,昭和5年のことであった.しかし,当時の未発達なエレクトロニクス技術環境下では,その実用化への道のりは,苦難の旅立ちにも似た険しいものがあったと伝えられている.本橋では,ソフトフェライトを中心とする電波吸収体技術について,基礎事項から説き起こし,電波吸収材としてのフェライト,電波吸収特性を支配する透磁率特性などについて述べた後,新しい電波吸収体の考え方として,筆者が提案している材料定数等価変換法について紹介する.とくに,電波吸収原理について,上記仏教哲理を踏まえての解説を試みている.

著者

倉田 啓明 白川 究 中島 冶 村上 孝一

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.17, no.2, pp.537-540, 1993-04-01 (Released:2007-12-03)

参考文献数

5

被引用文献数

1 1

---

For miniaturization of magnetic devices, it is necessary to increase the operating frequency. We have studied thin-film micro-inductors to realize a high operating frequency and reduce the iron loss. In this paper, we propose a thin-film micro-transformer with high operating frequency achieved by application of a multilayered magnetic film to the core. The magnetic core is made of amorphous CoFeSiB monolayer film or a CoFeSiB/SiO2 multilayered film. The induced magnetic anisotropy is controlled so that the exciting direction of the coil is along the hard axis. The total thickness of the magnetic layer is 3μm and the size of the core is 0.6 mm × 2.3 mm. The experimental transformers show that a multilayered core is useful for improving the transmission loss of transformers at high operating frequency. A thin-film transformer whose transmission loss is 2.7 dB from 100 MHz to 250 MHz has been developed. This value is smaller than the 5.3 dB of the monolayer core.

著者

中村 健二 木村 幸四郎 一ノ倉 理

出版者

公益社団法人日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:18804004)

巻号頁・発行日

vol.28, no.4, pp.602-606, 2004-04-01

被引用文献数

6

---

A switched reluctance motor (SRM) has such desirable features as simple construction, high reliability, and low cost. The SRM has not, however, been put into wide application because of large torque ripple and acoustic noise. In addition, quantitative analysis and optimum design of the SRM have not been fully clarified. In a previous paper, we proposed a simple magnetic circuit model of an SRM based on its configuration. We calculated such dynamic characteristics of the SRM as excitation voltage, winding current, and flux in each part of the motor. In this model, however, reluctances of the stator and rotor cores are approximnated by a linear function. In order to improve the calculation accuracy, we have to consider nonlinear characteristics of the core material. Furthermore, local saturation occurring at stator and rotor pole-tips and leakage fluxes from the stator pole must be considered. In this paper, we examine a nonlinear magnetic circuit model of the SRM considering the local saturation at the pole-tips and the leakage fluxes.

著者

神宮寺 直子 山方 義彦 松木 英敏 星宮 望 古川 孝

出版者

公益社団法人日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:18804004)

巻号頁・発行日

vol.21, no.4, pp.693-696, 1997-04-15

被引用文献数

6 2

---

Cross coils that operate in an alternating magnetic field are proposed for transmitting signals. They cancel the noise induced by a symmetric magnetic field stem from a transcutaneous power-transmitting coil, and then transmit and detect the signals in the magnetic field. In comparison with figure-of-eight coils, cross coils keep a certain senditivity due to dislocation between the transmitting and detecting coils. The signal-transmitting ability of cross coils is not very high, but above properties make them useful as transcutaneous signal-transmitting coils.

著者

近角 聰信

出版者

(社)日本応用磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.4, no.2, pp.44-47, 1980-05-31 (Released:2010-05-18)

参考文献数

23

被引用文献数

1

---

After describing a history of Invar alloys, analyses of anomalous temperature dependence of Fe-Ni Invar alloys are introduced. The anomalous magnetic and elastic properties of the same alloys are wellcorrelated with that of thermal expansion. Effect of high magnetic field and that of cold-rolling are also described.

著者

山口 正洋 薮上 信 中田 浩一 荒井 賢一 板垣 篤 板垣 喜一 斎藤 昇 布田 孝一 渡辺 光春 高橋 洋 田母神 隆 桜田 幸雄

出版者

公益社団法人日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:18804004)

巻号頁・発行日

vol.22, no.4, pp.849-852, 1998-04-15

被引用文献数

3

---

We developed a near-field magnetic noise mapping system by using a shielded-loop type coil array. High-resolution(01.mm)two-dimensional magnetic field vector detection was realized. We demonstrated a noise map of the loop antenna, microstrip line, and printed circuit board of a personal computer.