• 한국안전학회지
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• 제30권4호
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• pp.8-13
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• 2015

The magnetic shape memory alloys have recently received a lot of attention due to the considerable progress achieved in understanding the particular importance and the development of the factors. Among these alloys, the ferromagnetic Co-Ni- alloys have been concerned specially because of the thermoelastic character of the fcc (g) - bct (a) martensitic transformation which exhibits under the action of the temperature (shape memory effect), the stress (superelasticity) and the magnetic field (magnetoelasticity). The morphological, the crystallographical, and the thermal characteristics of thermally induced martensite in Co-35.3Ni-11.3Al(wt.%) and Co-28.1Ni-47.4Fe-3.3Ti (wt.%) alloy have been investigated by the scanning electron microscope (SEM), the X-ray Diffraction (XRD), and the differential scanning calorimeter (DSC).

• Journal of Magnetics
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• 제15권2호
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• pp.56-60
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• 2010

In this study, we investigated the optical, magnetic, and electrical transport properties of $Si_{1-x}Mn_x$ (0.1 < x < 0.9) single crystals grown by the vertical Bridgman method. The alloys with a Mn concentration of up to 64% demonstrated weak ferromagnetic ordering around $T_C=30\;K$. The $Si_{0.25}Mn_{0.75}$ and $Si_{0.18}Mn_{0.82}$ alloys showed weak ferromagnetic ordering at 70 K and antiferromagnetic ordering at 104 K, as confirmed by magnetization, neutron diffraction, and transport studies.

• 한국세라믹학회지
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• 제32권4호
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• pp.436-440
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• 1995

Effects of microstructure of two Mg-ferrite specimens with the same starting composition and relative density but with different grain size on B-H hysteresis loop, natural resonance frequency, and ferromagnetic resonance line width are reported. Such properties as B-H hysteresis loop, saturation magnetization, natural resonance frequency, and ferromagnetic resonance line width were influenced by the microstructure development during sintering. Large grain size specimen showed high saturation magnetization, low coercive force, low natural resonance frequency, and low ferromagnetic resonance line width compared with the specimen of small grain size. The main reason for the changes in properties can be explained by the variation in anisotropic characteristics due to Fe+2 content generated during sintering process.

• Journal of information and communication convergence engineering
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• 제8권1호
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• pp.95-98
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• 2010

The Electro Magnetic (EM) Acceleration and Deceleration (ACC/DCC) system of the Ferromagnetic Ball(FB) is the linear motor's final structural development which can be used for devices that conserve energy, gaming or rail gun. By accelerating the FB within the coil structure, it is difficult to utilize the FB's magnetizing feature via the ACC/DCC system. There is much monopole space inside the monopole coil. By using this particular feature of the FB, starting coil and Monopole Coil Structure (MCS) can be structurally separated and another simple electric related control system can be experimented for further development. For the purpose of development a review is needed of the control system of both basic stepper motor and BLDC motor.

• 한국공작기계학회논문집
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• 제13권6호
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• pp.74-80
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• 2004

An internal finishing process by the application of magnetic abrasive machining has been developed as a new technology to obtain a fine inner surface of pipe. In this paper, the finishing process of a non-ferromagnetic pipe by a static magnetic field method is introduced and its finishing characteristics is discussed with effective factors by various experiments. From these experimental results, it is found that the magnetic abrasives inserted in the pipe are arranged according to the magnetic force line. Through the experimental, it is possible to estimate the proper supply volume of the abrasive, which in proportional to the diameter of pipe.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 하계학술연구발표회 및 한.일 공동심포지엄
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• pp.262-262
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• 2003

Creating a new spin-based electronics (often called "spin-electronics" or "spintronics") is one of the hot topics in the current solid-state physics and electronics research. In order to utilize the spin degree of freedom in solids, particularly in semiconductors the current electronics is based on, we need to fabricate appropriate materials, understand and control the spin-dependent phenomena. In this ta1k, I will review the recent deve1opments of epitaxial ferromagnetic hetero structures based on semiconductors towards spintronics. This includes the semiconductor materials and hetero structures having high ferromagnetic transition temperature (III-V based alloy magnetic semiconductors, Mn-delta-doped magnetic semiconductors, and related heterostructures), spin-dependent transport and tunneling, and their device applications (tunneling magnetoresistance devices and three-terminal devices). Future issues and prospects will be also discussed.

• 한국자기학회지
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• 제3권2호
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• pp.125-129
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• 1993

강자성 공명 실험을 사용하여 고주파 마그네트론 스파터링 방법으로 제작된 $Co_{79}Cr_{21}(at.%)$ 박막의 자기적 특성을 조사하였다. $Co_{79}Cr_{21}$ 박막은 $K=2.91{\times}10^{5}\;erg/cm^{3},\;H_{k}'=2526\;Oe,\;g=2.17$인 특성을 보이며, Q-band 강자성 공명 실험 결과와 토오크 실험결과는 서로 잘 일치함을 볼 수 있었다.

• 한국재료학회지
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• 제13권9호
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• pp.561-566
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• 2003

Mechanical alloying(MA) process using elemental powders followed by hot pressing has been applied to some intermetallic alloy system containing ferromagnetic elements, such as NiAl and $FeSi_2$. A modified thermogravimetric analysis (TGA) technique was used to investigate the degree of alloying in milled powders and hot consolidated specimens as well as heat-treated bulk specimens. It is shown that the measurement of Curie temperatures in MA intermetallic powders and consolidated specimens containing ferromagnetic components, when determined as a function of milling and heat treatment parameters, can give some insight into the progress and mechanism of alloying.

• Journal of Magnetics
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• 제18권2호
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• pp.155-158
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• 2013

FeCoB films were being prepared on a Ru underlayer by using the oblique incidence of sputtered and back-scattered particles which have a high in-plane magnetic anisotropy field $H_k$ above 400 Oe. It is suitable to attain such deposition condition when facing targets sputtering system. The in-plane X-ray diffraction analysis clarified that there is anisotropic residual stress which is the origin of the high in-plane magnetic anisotropy. The directional crystalline alignment and inclination of crystallite growth were also observed. Such anisotropic crystalline structures may affect the anisotropic residual stress in the films. The B content of 5.6 at.% was appropriate to induce such anisotropic residual stress and $H_k$ of 410 Oe in this experiment. The film with B content of 6 at.% possessed large saturation magnetization of 22 kG and high $H_k$ of 500 Oe. The film exhibited high ferromagnetic resonance frequency of 9.2 GHz.

• 한국전기전자재료학회논문지
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• 제18권11호
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• pp.1056-1060
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• 2005

We investigated the fabrication and characteristics of the nitride-based spin-polarized LEDs with room-temperature ferromagnetic (Ga,Mn)N layer as a spin injection source. The (Ga,Mn)N thin films having room-temperature ferromagnetic ordering were found to exhibit the negative MR and anomalous Hall resistance up to room temperature, revealing the existence of spin-polarized electrons in (Ga,Mn)N films at room temperature. The electrical characteristics in the spin LEDs did not degraded in spite of the insertion of the (Ga,Mn)N layer into the LED structure. In EL spectra of the spin LEDs, it is confirmed that the devices produce intense EL emission at 7 K as well as room temperature. These results are expected to open up new opportunities to realize room-temperature operating semiconductor spintronic devices.