• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05a
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• pp.13-16
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• 2003

Magnetic and magneto-optical properties of Fe/Pt/Fe, Co/Pd/Co trilayers and also the sandwiches with wedge-shaped magnetic (Fe, Co) and nonmagnetic (Pt, Pd) layers were investigated. The oscillatory behavior of the saturation field $H_{s}$ of the studied trilayers with changing the thickness of the nonmagnetic layer (NML) $t_{NML}$ was revealed. That was explained by the exchange coupling between ferromagnetic layers (FML) through the nonmagnetic spacer. For the first time, oscillations of the transverse Kerr effect (TKE) with changing the Pt- and Pd-wedge thickness were discovered. Period of these oscillations was found to depend on the FML thickness and the photon energy of the incident light. TKE spectra of the examined samples were discovered to modify very strongly with increasing $t_{NML}$. The discovered peculiarities of magneto-optical properties of thin-film systems were explained by a concept of the spin-polarized quantum well states in the pt and Pd layers.

• Journal of Magnetics
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• v.2 no.1
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• pp.1-6
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• 1997

The magnetic and magnetostrictive properties of melt-spun ribbons of the alloys (R0.33Fe0.67)1-xBx (R=Tb0.3Dy0.7 and 0$\leq$x$\leq$0.06) are ivestigated as a function of wheel speed during melt-quenching. The saturation magnetiation of the alloys with a crystalline phase ranges from 70 to 80 emu/g and does not vary substantially with the B content. The saturation magnetization of an amorphous phase, which is formed at the condition of thigh wheel speed and high B content, is reduced significantly, however. The coercive force is minimum at x= 0.02 and increases monotonously with the further increase of B content when the microstructure mainly consists of a crystalline phase, but again it is reduced significantly by the formation of an amorphous phase. The low field sensitivity of magnetostriction with magnetic field is found to be good for the alloys with x$\leq$0.04 over a wide range of wheel speed. This magnetostrictive behavior is in contrast with that observed previously for Dy-Fe and Tb-Fe based alloys and is thought to be due to low intrinsic magnetocrystalline anisotropy of the compound.

• 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.

• Korean Journal of Materials Research
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• v.12 no.11
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• pp.880-882
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• 2002

We have prepared magnetic thin films of FeSiB by sputtering and examined microstructure and magnetic properties of the annealed films in order to investigate the feasibility of the films to microsensor application. Effects of vacuum annealing on the magnetic properties of $Fe_{84}$$Si_{6}$$B_{10}$ films have been examined as a function of temperature. The heating rate and the holding time were 10 K/min and 1 hour, respectively. Vacuum condition was held during cooling to prevent oxidation of the films. The coercivity did not show any noticeable change (~1500 A/m), although the grain size of the crystalline phase in the annealed films increased gradually up to about 16 nm until 673 K. However, both the grain size and the coercivity increased steeply when the annealing temperature increased over 723 K. Since the saturation magnetization is closely related to the phase evolution, the variation of the saturation magnetization of the annealed films was similar to that of the ribbon materials; the thin films were transformed from amorphous to crystalline with $\alpha$-(Fe,Si) phase by increasing annealing temperature.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.628-633
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• 1996

Large saturation magnetization $4pM_s$ is essentially required for soft magnetic thin layers used in magnetic recording devices. Amorphous Co-based alloys and Fe-Co alloys may be regarded as one of the candidates for soft magnetic materials which possess large $4\piM_s$. Some preparation process to improve soft magnetism of these films were performed in this study. Addition of Ta seemed to be effective to change the magnetostriction constant $\lambda$ from positive value to negative one. The magnetoelastic energy $K_e$ is strongly dependent on $\lambda$. $(Co_{95.7}Zr_{4.3})_{100-x}Ta_x$ films with $K_e$ of negative value have sufficiently soft magnetic characteristics. $Fe_{90}Co_{10}$ alloy exhibits extremely large $4\piM_s$, of about 24 kG. Addition of N and Ta to $Fe_{90}Co_{10}$ films improved the soft magnetism of them. The $Fe_{82.0}Co_{7.6}Ta_{10.4}$:N/Ti multilayered films exhibit better soft magnetic properties and better thermal stability than Fe-Co-Ta:N singlelayer films.

• Journal of Magnetics
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• v.21 no.1
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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.

• Korean Journal of Materials Research
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• v.33 no.3
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• pp.95-100
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• 2023

This research examines the effect of adding aluminum on the structural, phasic, and magnetic properties of CoCrFe NiMnAl_x high-entropy alloys. To this aim, the arc-melt process was used under an argon atmosphere for preparing cast samples. The phasic, structural, and magnetic properties of the samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrational magnetometry (VSM) analyses. Based on the results, the addition of aluminum to the compound caused changes in the crystalline structure, from FCC solid solution in the CoCrFeNiMn sample to CoCrFeNiMnAl BBC solid solution. It was associated with changes in the magnetic property of CoCrFeNiMnAl_x high-entropy alloys, from paramagnetic to ferromagnetic. The maximum saturation magnetization for the CoCrFeNiMnAl casting sample was estimated to be around 79 emu/g. Despite the phase stability of the FCC solid solution with temperature, the solid solution phase formed in the CrCrFeNiMnAl high-entropy compound was not stable, and changed into FCC solid solution with temperature elevation, causing a reduction in saturation magnetization to about 7 emu/g.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.117-124
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• 1994

The reduction of saturation magnetization in the Mg-Mn microwave ferrites was achieved by substituting the non-magnetic A1 ion for Fe ion. It is necessary for extending the operation frequencies that there is no change in other properties of the microwave ferrites. The electrical and magnetic properties are characterized where the composition of the ferrites studied was given by the general formula $(MgO)_{1.0}(MnO)_{0.1}(Al_xFe_{1.9-x}O_{2.85}$ with x ranging from 0.1 to 0.4. The saturation magnetization and the ferromagnetic resonance linewidth was decreased by the substituting amount of $Al_2O_3$. The value of coercive field was low enough over the composition of x=O.2 and the high squareness ratio was obtained all over the amount of substitution. It is feasible to select the proper application area with the combination of various properties ; that is, low coercive field, high squareness ratio, optimum saturation magnetization and ferromagnetic resonance linewidth.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1143-1146
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• 1993

The magnetic properties of aluminium anodized film in which Co-Fe alloy electrodeposited are investigated with regard to the alloy composition of magnetic films. The electrodeposited Co-Fe particles are confirmed to be single phase Co-Fe alloys by X-ray diffractions. The coercive force as well as the magnetic anisotropy energy can be controlled by changing the composition of the alloy. Magneticfilms having high saturation magnetization and high coercive force were obtained.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.343-350
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• 1995

An overview will be given on recent Mossbauer and magnetization investigation of the applied field dependence of the magnetic properties of typical systems without strong magnetic anisotropy and showing the absence of magnetic saturation in high fields (including iron-rich spin glass (amorphous $Fe_{93}Zr_{7}$, soft ferromagnets (amorphous $Fe_{88}Zr_{12}$, $Fe_{70}Ni_{20}Zr_{10}$ and $Fe_{88}B_{12}$) and pure Fe). The results emphasize that shape anisotropy due to surface irregularities causes misalignment between the magnetization and the applied field in the otherwise collinear magnetic structure.