• Journal of the Korean Magnetics Society
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• v.6 no.2
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• pp.112-116
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• 1996

스퍼터링법으로 제조한 NiFeCo/Cu/NiFeCo/FeMn 스핀밸브 자성 다층막의 자기적 성질과 자기저항에 대해 연구하였다. Cu 사잇층 두께가 15 .angs. 인 경우 약 6%의 자기저항을 얻을 수 있었다. NiFeCo/FeMn에서 교환이방성 자계는 약 20 Oe 정도였는데, 이는 NiFe/FeMn 계 스핀밸브 구조에서 보고된 값(100 Oe 이상) 보다 현저히 작은 것이다. 3 mTorr에서 제조한 NiFeCo 박막은 약 10 Oe 정도의 큰 보자력을 보임으로써 비슷한 조건에서 제조한 NiFe 박막의 경우(약 2 Oe)보다 상당히 큰 값을 갖는 것으로 관찰되었다. 작은 교환이방성 자계와 큰 보자력으로 인해 음 .rarw. 양 방향과 양 .rarw. 음 방향의 자화거동에 있어서 비대칭적인 자기저항 이력곡선 거동을 보이는 것으로 나타났다.

• Journal of the Korean Magnetics Society
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• v.27 no.4
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• pp.123-128
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• 2017

The magnetic isotropy property from the magnetoresistance (MR) curve and magnetization (MH) loop for the PtMn based spin valve (SV) multilayer films fabricated with different the bottom structure after post-annealing treatment was investigated. The exchange biased coupling field ($H_{ex}$), coercivity ($H_c$), and MR ratio of Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/Ta(4 nm) SV multilayer film without antiferromagnetic PtMn layer are 0 Oe, 25 Oe, and 3.3 %, respectively. MR curve for the Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/PtMn(6 nm)/Ta(4 nm) SV multilayer film showed $H_{ex}=2Oe$, $H_c=316Oe$, and MR (%) = 4.4 % with one butterfly MR curve having by the effect of antiferromagnetic PtMn layer. MR curve for the dualtype Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/PtMn(6 nm)/CoFe(3 nm)/Cu(2.5 nm)/CoFe(6 nm)/Ta(4 nm) SV multilayer film showed $H_c=37.5Oe$ and 386 Oe, MR = 3.5 % and 6.5 % with two butterfly MR curves and square-like hysteresis MH loops. The anisotropy property in CoFe spin valve-PtMn multilayer is neglected by the effects of a very small value of $H_{ex}$ and a very slightly shape magnetic anisotropy. This result is possible to explain the effect of magnetization configuration spin array of the bottom SV film and the top SV film of PtMn layer.

• 한국지구물리탐사학회:학술대회논문집
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• 2009.10a
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• pp.107-109
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• 2009

Micromagnetism explores magnetic configurations in nano-scales to visualize the details of magnetic domain structures, and also can produce snapshots of complex remanence or other magnetic states. The particle shape has a profound effect on the magnetic hysteresis. For instance, octahedral magnetite showed higher coercivity and squareness than cubic magnetite.

• Journal of the Korean Magnetics Society
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• v.19 no.6
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• pp.191-196
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• 2009

Magnetic bias phenomena of field-annealed CoFeSiB amorphous ribbons showing asymmetric giant magnetoimpedance was investigated by MOKE method. The specimens removed the crystalline layer at one surface side by chemical etching were prepared and measured magnetization curves by MOKE to investigate the effect of the crystalline layer on magnetization of inner soft amorphous phase. We observed the shift of hysteresis loop, and concluded that the crystalline layer exerts bias field effect on inner soft amorphous phase and the direction of bias filed is opposite to the magnetization direction of surface crystalline layer.

• Journal of the Korean Magnetics Society
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• v.7 no.4
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• pp.212-216
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• 1997

A pulsed field magnetometer with maximum applied field of 130 kOe has been constructed. The pulsed field generated by a 18 kJ capacitor bank system combined with a pulse coil was damped oscillation with the period of 10.12 ms. Magnetic hysteresis loop was measured by induction method during 10.12 ms of a pulse duration from the first positive to the second positive peak. The difference from DC magnetic properties due to the eddy current effect was inferred below 3% for the NdFeB magnet with the diameter below 5 mm.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.2
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• pp.115-120
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• 2018

This paper introduces a magnetic hysteresis monitoring result to apply an EM sensing technique for estimating tensile force of PSC girder to various class of PS tendon. The tensile force of PS tendon is a very important factor in the performance evaluation of PSC bridges. However, in this time, the tensile force was just measured only during construction and it does not monitored after construction. To measure the tensile force of PS tendons, the EM sensing based NDT method was developed but the proposed method cannot be applied to various class of PS tendons. Thus this study performed the magnetic hysteresis measurement according to the tensile force for class B, C and D PS tendons through experimental study. The specific tensile forces(50, 100, 150, 180kN) were induced to the each specimens and the magnetic hysteresis curve was measured at each point. The permeability of specimens were gradually decreased according to increase of tensile force. Especially, the slopes of permeability variation of class B and C were similar while that of class D was different.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.2
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• pp.255-261
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• 2003

It is advantageous to use NDE methods to assess the mechanical properties of materials since the conventional method is time-consuming and sometimes requires cutting of sample from the component. The NDE parameters such as ultrasonic velocity and attenuation, electric resistivity, and magnetic coercive force and remanance have been utilized to evaluate changes of material properties due to heat treatment condition. It has been found that changes of materials properties under quenched and tempered/PWHT treatments could not be detected using EMAT and Electrical resistivity methods. However, victors hardness and magnetic hysteresis loop decreased with heat treatment procedures. These results were obtained using 3Cr-lMo-0.25V steel. The magnetic parameters were found to be most sensitive to changes of material properties.

• Electrical & Electronic Materials
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• v.8 no.6
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• pp.787-794
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• 1995

To improvement the magnetic and frequency properties of YIG(Yttrium-Iron Garnet) in microwave region, it is investigated that the effect of $Al^{3+}$ ions on magnetic and frequency characteristics of YIG, using samples of basic YIG composition( $Y_{3}$F $e_{5}$ $O_{l2}$) added with A1$_{2}$ $O_{3}$ from 0 to 2.5 [mol%]. The measurment is conducted mainly for the structural properties and magnetical properties. The structural properties is measured using SEM(Scanning Electro Microscope), EDX(Energy-dispersive X-ray spectrometer) and XRD(X-ray diffraction equipment). The magnetical properties is measured with B-H curve tracer and impedance analyzer. As a result, it is confin-ned that the effect of eddy current loss is minimized while maintaining high saturation flux density of YIG, when YIG is added with 0.5 [mol%] of A1$_{2}$ $O_{3}$.>.>.

• Journal of the Korean Magnetics Society
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• v.19 no.4
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• pp.133-137
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• 2009

$MnGeP_2$ thin films grown on GaAs exhibit room-temperature ferromagnetism with $T_C{\sim}$320 K, based on both magnetization and resistance measurements. The coercive fields at 5, 250, and 300 K are 3870, 1380 and 155 Oe, respectively. The anomalous Hall effect was observed, indicating spin polarization of the carriers. Hysteresis has been observed in both magnetoresistance and Hall measurements. The current-voltage characteristics of a $MnGeP_2$ film grown on an n-type GaAs substrate display semiconducting behavior.

• Electrical & Electronic Materials
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• v.3 no.4
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• pp.306-314
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• 1990

SrO-5.7Fe$_{2}$O$_{3}$의 Magnetoplumbite형 Sr페라이트에 첨가제 SiO$_{2}$, H$_{3}$BO$_{3}$CaCO$_{3}$, SrCO$_{3}$을 0.1-0.1wt%로 변화시켜 만든 등방성과 이방성의 자기이력곡선, 밀도, 감자곡선, 고유보자력 및 미세구조특성에 미치는 영향을 조사하였다. 위 첨가제는 페라이트 생성 및 특성개선에 효과적이었도 특히 등방성에서의 입도크기를 3.5.mu.m에서 1.7.mu.m로 하였을때 소결온도가 40.deg.C 낮은 1220.deg.C에서 잔류자속밀도가 2300G, 보자력이 1950Oe, 밀도가 4.51g/Cm$^{3}$, 교유보자력이 3500Oe로 각각 증가하였다. 이방성은 등방성 보다 원등히 우수하였고 최대에너지적 (BH)$_{max}$이 소결온도가 10.deg.C 낮은 1210.deg.C에서 1.13으로 부터 3.3MGOe로 증가하였다. 이값은 이론치의 61%에 도달하고 있다.