• 전기학회논문지
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• 제56권12호
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• pp.2116-2121
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• 2007

Numerical identification of synthetic d-q flux linkage, representative parameters for analyzing interior buried PM synchronous Motor(IPMSM) with distinguished magnetic saturation, has been peformed. Particularly, numerical identification of synthetic flux linkage using modified Finite Element Method(F.E.M) has been taken cross-magnetization of multi-layered PM configuration into consideration. Futhermore, experimental identification on the purpose-built prototype has been made to verify the validity of the numerically identified synthetic d-q flux linkages.

• 대한금속재료학회지
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• 제50권3호
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• pp.248-255
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• 2012

AlN thin films containing various amounts of Co, AlN-Co, and Al-Co alloy particles were prepared using a two-facing-target type dc reactive sputtering (TFTS) system. The as-deposited films exhibited the variable nature expected from an AlN-rich phase, and an amorphous-like phase, depending on the Co content in the films. Specific favorable microstructures were prepared by optimizing annealing conditions. Those microstructures and their magnetic properties and resistivity were investigated. As-deposited films showed very small saturation magnetization and an amorphous-like structure. However, when annealed, the as-deposited amorphous-like phase decomposes into phases of AlN, Co and Al-Co. These annealing induced changes in the microstructure improve the magnetization and resistivity of the films. Further improvement of soft magnetic properties could lead to the material being used for high density magnetic recording head material.

• 한국분말재료학회지
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• 제21권6호
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• pp.429-433
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• 2014

This study investigated the magnetic properties and frequency dispersion of complex permeability of Ni-Zn-Co ferrites used for magnetic shielding in near field communication (NFC) system. The sintered specimens of $(Ni_{0.7}Zn_{0.3})_{1-x}Co_xFe_2O_4$ composition were prepared by the conventional ceramic processing. The coercive force and saturation magnetization were measured by vibrating sample magnetometer. The complex permeability was measured by RF impedance analyzer in the range of 1 MHz~1.8 GHz. The coercive force increased and saturation magnetization decreased with increasing the Co substitution. The real and imaginary parts of complex permeability decreased and the resonance frequency increased with Co substitution, which was attributed to the increase in crystal anisotropy field and reduction in saturation magnetization. The effect of Co substitution could be found in reducing the magnetic loss to nearly zero at the operating frequency of NFC (13.56 MHz).

• 한국전기전자재료학회논문지
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• 제16권8호
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• pp.744-751
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• 2003

Co-Pd alloy thin films prepared by a DC-sputter that have self-organized nano structure(SONS), are promising for high-density information storage media in information era. We prepared the samples by varying Pd contents of 0~8.1 wt% at the substrate temperatures of room temperature (RT) and 200 $^{\circ}C$, respectively Microstructure and Pd contents of the Co$_{1-x}$ Pd$_{x}$ films are probed by a scanning electron microscope (SEM), a transmission electron microscope (TEM) and an energy dispersive spectrometer (EDS). We also investigated the saturation magnetization (Ms), remanence and coercivity of the Co$_{1-x}$ Pd$_{x}$ films. Surface roughness are measured by an atomic force microscope (AFM). We revealed that self-organized nano size Co-enriched phase and Pd-enriched phase existed with Pd contents at the substrate temperatures of RT and 20$0^{\circ}C$ through microstructure characterization. SONS helped to keep the saturation magnetization and enhance the perpendicular anisotropy with Pd contents. Out result implies that we may tune the perpendicular magnetic properties with keeping the saturation magnetization by varying substrate temperatures and Pd contents for high density magnetic recording.rding.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2017년도 임시총회 및 하계학술연구발표회
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• pp.123-123
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• 2017

• 한국자기학회지
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• 제9권4호
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• pp.173-176
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• 1999

자장 중에서 정렬된 일축이방성 다결정분말의 자화곡선을 이용하여 포화자화와 결정자기이방성상수를 결정하는 방법의 오차를 분석하였다. 분말의 정렬도가 $10^{\circ}$일 때 Nd2Fe14B의 경우의 Ms 및 K1 오차는 각각 1% 및 13%였으며, Ba-ferrite의 경우 1% 미 17%이다. 이 방법으로 계산하여 Ms는 매우 정확하게 구할 수 있으며 정확도를 높이기 위해서는 분말의 정렬도를 증가시켜야함을 알았다.

• 한국전기전자재료학회논문지
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• 제27권7호
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• pp.462-467
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• 2014

In this paper, we studied the magnetic composite sheets for electromagnetic wave noise absorber of quasi-microwave band by using soft magnetic FeSiCr and Fe50Ni flakes with the thickness of about $1{\mu}m$ and polymer. The magnetic hysteresis curve including saturation magnetization and residual magnetization and the complex permeability characteristics of the composite sheets were investigated to clarify the mixing effect on electromagnetic wave absorption properties. The saturation magnetization was decreased about 10% while the residual magnetization was increased about 15% and the real parts of complex permeability at below 500 MHz were increased 0.6~4 while those values at above 500 MHz were decreased 0.4~2.5 according to the change of contents of FeSiCr and Fe50Ni powders. As a result, the reflection loss can be moved to the lower frequency from 2~3 GHz to 1~1.5 GHz as the contents of Fe50Ni flaky powder into FeSiCr flaky powder was increased up to 50%.

• 한국자기학회지
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• 제1권2호
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• pp.55-59
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• 1991

희토류-3d 천이원소인 비정질${[{(Fe_{80}CO_{20})}_{0.98}RE_{0.02}]}_{80}B_{20}(RE=Nd,\;Sm,\;Gd,\;Tb)$ 합금 리본시료에 대한 자기적 성질을 조사하기 위하여 시료진동형 자력계(vibrating sample magnetometor)를 이용하여 77 K부터 900 K까지의 온도 영역에서 포화자화 값을 온도의 함수로 측정 한후, Curie 온도 ($T_{c}$)와 Bloch 상수등을 추정하였다. 이들로 부터 spin wave stiffness 상수, 교환상호작용(exchange interaction)의 범위와 평균자승거리($$)등을 계산하였으며 각 희토류 원소에 대한 치환효과를 비교 분석하였다.

• Journal of Magnetics
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• 제21권1호
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• pp.6-11
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• 2016

The magnetic anisotropy energy (MAE) and the saturation magnetization $B_s$ of (110) $Fe_nCo_n$ heterostructures with n = 1, 2, and 3 are investigated in first-principles within the density functional theory by using the precise full-potential linearized augmented plane wave (FLAPW) method. We compare the results employing two different exchange correlation potentials, that is, the local density approximation (LDA) and the generalized gradient approximation (GGA), and include the spin-orbit coupling interaction of the valence states in the second variational way. The MAE is found to be enhanced significantly compared to those of bulk Fe and Co and the magnetic easy axis is in-plane in agreement with experiment. Also the MAE exhibits the in-plane angle dependence with a two-fold anisotropy showing that the $[1{\overline{I}}0]$ direction is the most favored spin direction. We found that as the periodicity increases, (i) the saturation magnetization $B_s$ decreases due to the reduced magnetic moment of Fe far from the interface, (ii) the strength of in-plane preference of spin direction increases yielding enhancement of MAE, and (iii) the volume anisotropy coefficient decreases because the volume increase outdo the MAE enhancement.

• 한국자기학회지
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• 제5권5호
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• pp.496-499
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• 1995

Amorphous $Co_{80+x}TM_{12}B_{8-x}$ (TM = Ti, Zr, Hf, Nb and x = 0, 2, 4 at%) alloys were prepared by single roll melt spinning technique. Saturation magnetization of the amorphous ribbons was measured by SQUID and vibrating sample magnetometer from 5 to 800 K under applied fields up to 10 kOe. Typical thermo-magnetization curves were observed and the average values of the spectroscopic splitting g factor were estimated from the ferromagnetic resonance curve. For all the amorphous alloys studied here the saturation magnetization in the temperature range 5 K up to about $0.3T_{c}$ can be described by the Bloch relation: $M_{s}(T)\;=\;M_{s}(0)(1-BT^{3/2}-CT^{5/2})$. From the values of $M_{s}(0)$, B and spectroscopic splitting g factor the spin wave stiffness constants were calculated.