• Journal of the Korean Magnetics Society
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• v.9 no.4
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• pp.173-176
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• 1999

Errors of saturation magnetization and magnetocrystalline anisotropy constant determined by magnetization curve of magnetically aligned unixial power were analyzed. In case of alignment factor ${\Theta}_0=10{\circ}$, magnetic constant errors of $Nd_2Fe_{14}B$ were calculated to be error of $M_S{\risingdotseq}1{\%}\;and\;error\;of\;K_1{\risingdotseq}13\;{\%}$, respectively, and magnetic constant errors of Ba-ferrite were calculated to be error of $M_S{\risingdotseq}1{\%}\;and\;error\;of\;K_1{\risingdotseq}17\;{\%}$. In this method, $M_s$ was found to be determined with high accuracy. High alignment is desirable for high accuracy.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1968-1970
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• 1999

본 연구에서는 RF 마그네트론 스퍼터링법으로 CoNbZrPd 비정질 연자성 박막을 제조하여 Pd의 첨가 효과와 자장중 열처리에 의한 특성 변화에 대해 연구하였다. Pd가 4.34 at% 첨가된 $Co_{87.56}Nb_{6.45}Zr_{1.65}Pd_{4.34}$ 박막은 비정질 구조이며 Pd 첨가에 의해 보자력은 0.54 Oe으로 감소하였으며, 이방성 자계는 10.45 Oe로 Pd를 첨가하지 않은 CoNbZr 비정질 박막 보다 특성이 향상되었다. $Co_{87.56}Nb_{6.45}Zr_{1.65}Pd_{4.34}$ 비정질 박막은 $400^{\circ}C$까지 비정질 상을 유지하고 있지만, 연자기 특성이 열화되어 보자력이 증가하고 이방성자계가 급격히 감소하였지만, 포화 자화는 크게 변화지 않았다.

• Journal of the Korean Vacuum Society
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• v.2 no.4
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• pp.455-461
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• 1993

Glass와 실리콘 웨이퍼(p-type(100), $ ho$=6~8$\Omega$-cm)를 기판으로 하여 NiFe/glass , NiFe/Si, NiFe/Al/Si, NiFe/Ti/Si 의 박막을 제작하였다. 하지층으로 사용한 알루미늄과 티타늄은 RF 스퍼터링으로 증착하였으며 퍼럼로이(NiFe) 필름은 60, 80, 90wt%Ni로 조성을 변화시켜 증착하였다. 박막의 포화자화(Ms), 보자력(Hc), 각형비(F)는 sweep time을 1.7분으로 하여 시료 토크마그네토 메터로 측정하였다. 보자력에 영향을 주는 표면조도는 전자주사현미경(SEM)과 표면조도 측정기로써 알아보았다. 실험결과 80wt% Ni 의 퍼멀로이에서 자장 중 열처리(35 Oe,$ 350^{\circ}C$) 후 약 1의 각형비를 나타내었으며 열처리 후 보자력이 떨어짐을 보였다. 자기이방성은 알루미늄을 하지층으로 한 퍼멀로이 박막에서 가장 좋은 값(Ku=-9.60 $\times$106 emu/㎤)을 나타내었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.6
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• pp.294-302
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• 2023

Ni-Mn-Zn ferrite, Ni_0.5-xMn_xZn_0.5Fe₂O₄ (0 ≤ x ≤ 0.5), was synthesized using the sol-gel method to investigate the crystal structure, microstructure, magnetic properties, high-frequency characteristics, and electromagnetic (EM) wave absorption characteristics as a function of Mn substitution. As the Mn content increased, a continuous decrease in saturation magnetization (M_S) was observed with little change in coercivity (H_C). Samples for each composition (x) exhibited strong EM wave absorption performance with first and second strong EM wave absorption regions satisfying minimum reflection loss, RL_min < -40 dB in the 1.5~2.5, 6~11 GHz range, respectively. The EM wave absorption in Ni-Mn-Zn ferrite depends on magnetic loss, and adjusting µ' and µ'' spectra by Mn substitution or H field allows control of the EM wave absorption frequency.

• Journal of the Korean Magnetics Society
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• v.20 no.1
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• pp.8-12
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• 2010

The magnetostriction and stress of multilayer $NiFeCr/(Cu/Co_{90}Fe_{10}){\times}N/NiFeCr$ films were investigated. As the number of Cu $15{\AA}$/CoFe $15{\AA}$ bilayers was increased, the saturation magnetostriction decreased from $-5.6\times10^{-6}$ at 2 bilayers to $-8.5\times10^{-6}$ at 20 bilayers. A change of CoFe thickness from 10 to $20{\AA}$ caused a decrease in the magnitude of tensile stress from 980MPa to 590MPa as the number of Cu $15{\AA}$/CoFe $15{\AA}$ bilayers increased from 2 to 20. The maximum magnetostrictive anisotropy field that could be developed due to nonzero magnetostriction and stress is calculated to be 135.7 Oe when the number of Cu $15{\AA}$/CoFe $15{\AA}$ bilayers is 10.

• Journal of the Korean Magnetics Society
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• v.9 no.2
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• pp.91-97
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• 1999

YIG $(Y_3Fe_5O_{12})$ films with 4~80 ${\mu}{\textrm}{m}$ thickness were epitaxially grown on GGG $(Gd_3Ga_5O_{12})$ substrates by LPE (liquid phase epitaxy) techniques. Using various melts having different chemical composition the growth temperature was varied as a parameter. Growth rate, surface morphology, chemical composition, lattice constant, saturation magnetization, and magnetic resonance of the films were investigated. Lattice mismatch between the substrate and film Δa, saturation magnetization, and magnetic resonance line width ΔH increased, decreased, and increased, respectively, as undercooling temperature ΔT increased. The films grown by using the melt with larger R$_1$and smaller R$_3$had smaller ΔH. The major origin of the increase of ΔH was the increase of Δa. It is considered that the magnetic field in the film became locally inhomogeneous with the increase of Δa due to the increase of inhomogenity in stress distribution to the film depth direction. Therefore, in order to grow YIG films with small microwave loss it is necessary to grow films at small ΔT using the melt with large R$_1$and small R$_3$resulting in a small Δa.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.474-479
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• 1993

An interferometric fiber-optic magnetic field sensor is constructed by bonding a Co-Fe-B metallic glass transducer developed here by the melt-spun method to a single mode fiber arm in the fiber Mach-Zehnder interferometer and is tested. The bias field for the peak ac-sensitivity was observed near 0.97 Oe and the minimum detectable magnetic field was 3.9${\times}10^{-5}$ Oe(rms)/${\sqrt{Hz}}$ a 3 kHz. The output of the ac field sensor becomes saturated near the input signal level of 1 Oe(rms). The Co- Fe-B transducer exhibits peak response near 500 Hz.

• Journal of the Korean Magnetics Society
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• v.14 no.1
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• pp.33-37
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• 2004

Cu$_{0.1}$Fe$_{0.9}$Cr$_2$S$_4$ has been studied with Mossbauer spectroscopy, x-ray diffraction, vibrating sample magnetometer (VSM), and magnetoresistance (MR) measurement. The crystal structure was determined to be a cubic spinel with lattice parameter a$_{0}$=9.9880 $\AA$. The MR measurements show a semiconductor behavior below 110 K and metal behaved above 100 K. The temperature dependence of magnetization of Cu$_{0.1}$Fe$_{0.9}$Cr$_2$S$_4$ was reported. In addition to a large irreversibility between the zero-field-cooling (ZFC) and the field-cooling (FC) magnetization at applied field H=100 Oe, a cusp-like anomaly was observed in both the FC and ZFC curves. It shifted toward the lower temperature region with increasing magnetic field, and then showed convex type maximum at 110 K, under the applied field of 5 kOe. The Mossbauer spectra were measured from 15 K to room temperature. The asymmetric line broadening was observed for the sample Cu$_{0.1}$Fe$_{0.9}$Cr$_2$S$_4$, and it was considered to be dynamic Jahn-Teller relaxation. The charge state of Fe ions was ferrous in character. The unusual reduction of magnetic hyperfine field below 110 K was interpreted in terms of cancellation effect between the mutually opposite orbital current field (H$_{L}$) and Fermi contact field (H$_{C}$).

• Journal of the Korean Magnetics Society
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• v.10 no.6
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• pp.269-273
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• 2000

Fe-l7Cr-2M(M=Si, Nb, Mo) alloy powder was prepared by plasma electrode rotating atomizer and than the alloy powder was formed and sintered. The particle shape of the Fe-l7Cr-2M(M=Si, Nb, Mo) alloy power is spherical. The saturation magnetization of the sintered Fe-17Cr-2Mo and Fe-l7Cr-2Nb alloy are 155 emu/g. The saturation magnetization of the sintered Fe-l7Cr-2Si alloy is less than that of the sintered Fe-l7Cr-2Mo and Fe-l7Cr-2Nb alloy. The amplitude relative permeability of the sintered Fe-l7Cr-2M(M=Si, Nb, Mo) alloy has the maximum value in the range of 3∼5 Oe applied field at forming pressure 12 ton/cm$^2$, sintering temperature 1200$^{\circ}C$, and frequency 1 kHz. Power loss of the sintered Fe-l7Cr-2Nb alloy is 40 mW/cc at applied field, H$\sub$a/=5 Oe, and frequency, f=1 kHz. The power loss of the sintered Fe-l7Cr-2Nb alloy is a half of that of the sintered Fe-l7Cr-2Si and Fe-l7Cr-2Mo alloy.

• Journal of the Korean Magnetics Society
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• v.11 no.6
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• pp.256-261
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• 2001

These experiments were carried out to examine the effects of element substitution of Zn and La-Zn for Sr-ferrite. The calcined properties of Zn and La-Zn element substitution were examined, and also the sintered magnetic properties were compared with the stoichiometric condition. The magnetization properties of calcined SrM materials is as follows; M$\_$s/ : 61.06 emu/g. Also, the magnetization properties of calcined Zn$\_$0.3/-SrM materials is as follows; M$\_$s/ : 66.90 emu/g. The sintered magnetic properties of (La-Zn)$\_$0.3/-SrM composition is as follows; B$\_$r/ : 4.21 kG, BH$\_$max/: 4.19 MGOe.