• Journal of the Korean Magnetics Society
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• v.14 no.6
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• pp.232-235
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• 2004

Linear GMR isolator which is profitable for transmitting analog signal was modeled and the output voltage and current in relation to the input current were investigated. GMR isolator modeling was divided into two parts, namely magnetic and electric parts. The flow chart of the modeling was drawn in which the MR curve of the spin valves were incorporated to obtain the electrical voltage output. For magnetic modeling, 3-dimensional model of planar coil was analyzed by FEM method to obtain the magnetic field strength corresponding to the input current. Coil efficiency of the planar coil having magnetic core layer was shown to have about 1.5 times larger than that of the coil without the magnetic core layer. The feedback coil current(output current) corresponding to the input coil current was calculated to be within ${\pm}$0.25 mA of the linear fitting function of I$\_$out/= I$\_$in/-5 mA. Also, the response time and output waveforms were obtained when the coil current was a rectangular waveform. The rise time and fall time was 6 ${\mu}\textrm{s}$, respectively when the slew rate of the op-amp was 0.3 V/${\mu}\textrm{s}$.

• Journal of the Korean Magnetics Society
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• v.22 no.5
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• pp.173-177
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• 2012

The multilayer structure of glass/Ta(5.8 nm)/NiFe(5 nm)/Cu(t nm)/NiFe(3 nm)/FeMn(12 nm)/Ta(5.8 nm) as typical GMR-SV (giant magnetoresistance-spin valve) films is prepared by ion beam sputtering deposition (IBD). The coercivity and magnetoresiatance ratio are increased and decreased for the decrease of Cu thickness when the thickness of nonmagnetic Cu layer from is varied 2.2 nm to 3.0 nm. It means that the decrease of non-magntic layer is effected to the interlayer exchange coupling of pinned layer and the spin configuration array of free layer. For experiment of detecting and dropping of magnetic beads we used the GMR-SV sensor with glass/Ta/NiFe/Cu/NiFe/FeMn/Ta structure. From the comparison of before and after for the dropping status of magnetic bead, the variations of MR ratio, $H_{ex}$, and $H_c$ are showed 0.9 %, 3 Oe, and 2 Oe, respectively. The fabrication of GMR-SV sensor was included in the process of film deposition, photo-lithography, ion milling, and MR measurement. Further, GMR-SV device can be easily integrated so that detecting biosensor on a single chip becomes possible.

• Proceedings of the Korean Magnestics Society Conference
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• 2015.05a
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• pp.161-163
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• 2015

The micro device, coil, and channel for the biosensor integrated with the GMR-SV device based on the antiferromagnetic IrMn layer was fabricated by the light lithography process. When RBCs coupled with several magnetic beads with a diameter of $1{\mu}m$ passed on the micro channel, the movement of RBC + ${\mu}Beads$ is controlled by the electrical AC input signal. The RBC + ${\mu}Beads$ having a micro-magnetic field captured above the GMR-SV device is changed as the output signals for detection status. From these results, the GMR-SV device having the width magnitude of a few micron size can be applied as the biosensor for the analysis of a new magnetic property as the membrane's deformation of RBC coupled to magnetic beads.

• Journal of Magnetics
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• v.2 no.3
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• pp.96-100
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• 1997

A spin valve structure of NiO(40 nm)/Co(2 nm)/Cu(2.6 nm)/Co(x nm)/Ta(5 nm) has been investigated for the application of magnetic random access memory (MRAM). The spin valve structure exhibited very large difference in the coercivities between pinned and free layers, a relatively high GMR ratio, and a low free layer coercivity. The spin valves were prepared by sputtering and were characterized by dc 4-point probe, and VSM. The spin valves with combined free layer exhibited a maximun GMR ratio of 10.4% with a free layer coercivity of about 82 Oe. The spin valves with a single 10 nm thick a-CoNbZr free layer exhibited a GMR ratio of about 4.3% with a free layer coercivity of about 12 Oe. The GMR ratio of the spin valves increased by addition of Co between Cu and a-CoNbZr. It has been confirmed that the coercivity of free layer can be decreased by increasing the thickness of a-CoNbZr. It has been confirmed that the coercivity of free layer can be decreased by increasing the thickness of a-CoNbZr layer without losing the GMR ratio substantially, which was mainly due to high resistivity of the amorphous "layers".

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.162-163
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• 2002

거대자기저항(GMR) 분야에서 높은 GMR 값을 보유하는 것은 주요 관심사이다. Egelhoff와 연구자들은 산소를 이용하여 스핀밸브 박막의 표면을 산화시켜 유도 전자들의 Specular 산란 효과를 보고하였으며, 강자성층과 산화층 사이의 계면에서 specular 반사가 이루어져 GMR의 향상을 가져온 것으로 보고 있다[1,2]. 또한 annealing에 따른 자기적 특성의 향상과에 관한 논문도 보고되어진 바 있다[4]. (중략)

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.78-83
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• 2003

Characterization of an ultra precision grinding plate for GMR head manufacturing is performed by measuring frictional forces between the grinding plate and the advanced ceramic Two kinds of methods of producing the precision grinding plates are presented: texturing and micro-channeling. Texturing is effective in terms of production time but micro-channeling excels in quality control. It is found that the frictional coefficient of a precision grinding plate decreases as the impregnation of diamond grain onto the precision-grinding plate progresses, and remains unchanged once the impregnation process is successfully completed, even after 100 revolutions of the precision-grinding plate against the advanced ceramic under 40 N of normal force. Therefore, the measurement of the frictional coefficient can replace costly and time-consuming process of estimating the level of impregnation of diamond grain on the precision-grinding plate, which has been performed by using scanning electron microscope, and be employed as an index to determine the level of impregnation of diamond grain.

• Proceedings of the Korean Magnestics Society Conference
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• 2012.11a
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• pp.146-148
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• 2012

미크론 자성비드 검출용 바이오센서에 활용하는 GMR-SV 박막을 이온빔 스퍼터링 증착법으로 glass/Ta(5.8 nm)/NiFe(5 nm)/Cu(t nm)/NiFe(3 nm)/FeMn(12 nm)/Ta(5.8 nm)의 구조를 갖도록 증착하였다. 비자성체 Cu의 두께가 3.0 nm에서 2.2 nm까지 얇아질수록 교환결합력은 증가하였으며 자기저항비는 다소 낮았다. 비자성체의 두께가 얇으면 반강자성체의 층간 교환작용이 강자성체의 고정층 뿐만 아니라 자유층의 스핀배열에도 영향을 주고 있음을 확인할 수 있었다. 또한 리소그래피 공정 과정을 거쳐 GMR-SV 소자를 제작하여 미트론 자기비드를 검출하였다. 여기서 자기비드를 떨어뜨리기 전과 후의 자기저항비, 교환결합력, 보자력은 각각 0.9%, 3 Oe, 2 Oe의 값을 나타내었다. 이것으로 미크론단위의 바이오센서로서 활용할 수 있는 가능성을 보여주었다.

• Journal of Magnetics
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• v.6 no.4
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• pp.129-131
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• 2001

In order to investigate the effect of the interface on GMR, [NiFe(25 ${\AA}$)/Cu(24${\AA}$)]$_2$/Si thin film was epitaxially grown on HF-treated Si (001) substrate using a DC magnetron sputtering method. Typical GMR effects could be observed in epitaxial film with a weak antiferromagnetic exchange coupling while non epitaxial film showed unsaturated and broad MR curves probably due to inter-diffusion between NiFe and Cu layers. Ferromagnetic resonance (FMR) experiment showed two distinct absorption peaks in all films. Each peak was revealed to come from each NiFe layer with different magnetic property. In FMR measurement very clear interface in epitaxial films could be confirmed by a lower value of line width (ΔH) and higher M$\sub$s/ of epitaxial film than those of non epitaxial films, respectively.

• Journal of Magnetics
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• v.22 no.1
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• pp.7-13
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• 2017

The magnetoresistance (MR) properties of antiferromagnetic (AFM) IrMn based giant magnetoresistance-spin valve (GMR-SV) was investigated in view point of the artificial rotation effect of ferromagnetic (FM) layer in the plane induced by an applied field during the post annealing temperature. The MR curves measured with an azimuthal angle region of ${\phi}=0^{\circ}-360^{\circ}$ are depended on the annealing temperature and the magnetization easy axis of two free NiFe layers and two pinned NiFe layers in dual-type GMR-SV film. Especially, the annealing temperature and sample rotation angle(${\theta}$ ) maintained to the magnetic sensitivity (MS) of 1.4 %/Oe with an isotropic region angle of $110^{\circ}$ are $100^{\circ}C$ and $90^{\circ}$, respectively.

• Journal of Magnetics
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• v.4 no.3
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• pp.80-83
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• 1999

Relations between giant magnetoresistance (GMR) characteristic, magnetic properties and structure were investigated in Cu90Co10 alloy obtained by melt spinning in which GMR was enhanced by appropriate annealing. The structure of the annealed sample is not homogeneous (though the sizes distribution of the majority of Co-particles is not very wide but much larger particles are also present). On the other hand, the GMR characteristics differs from that expected theoretically for identical superparamagnetic particles. It is shown that ther main sources of the observed non-quadratic magnetoresistance dependence on magnetization are differentialted surface to volume ratio of superparamagnetic particles and the ferromagnetic phase contribution to the total magnetization which was calculated applying the new method.