• Journal of Magnetics
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• v.7 no.3
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• pp.115-125
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• 2002

We proposed a novel method to evaluate the magnetic properties of the initial layer and the columnar structure separately for CoCr-based perpendicular recording media. We show that the thickness of the initial layer and the intrinsic magnetocrystalline anisotropy of columnar structure can be quantitatively evaluated using the plotted product of perpendicular anisotropy to magnetic film thickness versus magnetic film thickness ($K_{u{\bot}}^{ex{p.}}$ $\times$ d$_{mag.}$ vs. d$_{mag.}$ plot). Based on the analyses, it is found that: (1) compared with CoCrPtTa media, CoCrPtB media have relatively thin initial layer, and have fine grains with homogeneous columnar structure with c-plane crystallographic orientation; (2) CoCrPtB media can be grown epitaxially on Ru or CoCr/C intermediate layer, and as the result, the magnetic properties of the media within thin thickness region of d$_{mag.}$ $\leq$ 20 nm is significantly improved; (3) the key issue of material investigation for CoCr-based perpendicular recording media will be focused on how to fabricate c-plane-oriented columnar grains well isolated with nonmagnetic substance in epitaxial-growth media, while maintaining the thermal stability of the media.

• Transactions on Electrical and Electronic Materials
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• v.7 no.1
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• pp.42-50
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• 2006

Co-Fe-Al-O nano-granular thin films with high electrical resistivity, fabricated by radio frequency magnetron sputtering under an $Ar+O_2$ atmosphere, are found to show good soft magnetic properties in the GHz frequency range. The real part value of the relative permeability is 260 at low frequencies and this value is maintained up to the GHz frequency range. A non-integrated type noise filter on a coplanar waveguide transmission line is demonstrated by using the Co-Fe-Al-O nano-granular thin film with the dimensions of $4\;mm(l){\times}4\;mm(w){\times}0.1\;{\mu}m(t)$. The insertion loss is very low being less than 0.3 dB and this low value is maintained up to 2 GHz. At a ferromagnetic resonance frequency of 3.3 GHz, the degree of noise suppression is measured to be 3 dB. This level of noise attenuation is small for real applications, but there is much room for further improvement by increasing the magnetic volume and integrating the magnetic thin film into the CPW transmission line.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1098-1101
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• 1995

NbTi thin films were prepared on Si wafer and Cu substrate by rf magnetron sputtering in the range of sputtering pressure $3{\times}10^{-2}$torr to $3{\times}10^{-4}$torr at room temperature. The influence of sputtering pressure and substrate type on crystallographic orientation and morphology of NbTi thin films was investigated by using X-ray diffraction(XRD) and scanning electron microscopy(SEM), respectively. And the effect of crystallographic orientation and morphology of NbTi film on electromagnetic behaviors was estimated by measuring critical current in various applied magnetic field. The film morphology changed from porous structure consisting of tapered crystallites to densely deposited film decreasing with sputtering pressure. The change of crystallographic orientation with the sputtering pressure and rf power was calculated from the texture coefficient of(002) plane based on XRD patterns. It was found that a change of texture coefficient of(002) plane increased with decreasing sputtering pressure. From observation of critical current in various applied magnetic field, we have identified that the change of critical current abruptly decrease applying with magnetic field and NbTi film produced at high sputtering pressure does not exhibit superconductivity but at low sputtering pressure shows superconductivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.309-312
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• 1997

The Ce-Cr(-Ta) film are one of the most suitable candidates for perpendicular magnetic media. the control of the preparation conditions, such as Ar gas pressure P$\_$Ar/ substrates temperature T$\_$s/, films thickness $\delta$, deposition speed R$\_$d/, is considered to be important to attain ultra high density recording far perpendicular magnetic recording media. In this study, the Co-Cr thin films and Co-Cr-Ta thin films were deposited on the glass side substrates by using Facing Targets Sputtering apparatus(FTS). Crystallographic characteristics and magnetic characteristics were evaluated by X-ray diffractometry(XRD), Vibrating Sample Magnetometer(VSM) respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.6
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• pp.486-492
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• 1998

The amorphous Co-based magnetic films have a large saturation flux density, a low coercive force, and a zero magnetostriction constant. Therefore, they have been studied for application to magnetic recoding heads and micro magnetic devices. However, it was found that the magnetic anisotropy was changed for each film fabrication processes. In this study, we investigated how to control the anisotropy of sputtered amorphous $Co_{89}Nb{8.5}Zr{2.5}$ films. After deposition, the rotational field annealing ant the uniaxial field annealing were performed under the magnetic field of 1.5 kOe. the annealing was done at the temperature range from 400 to $600^{\circ}C$ for one hour. As-deposited amorphous $Co_{89}Nb{8.5}Zr{2.5}$ thin film had saturation magnetization ($4\piM_5$) of 0.8 T, coercive force($_IH_C$) of 1.5 Oe, and anisotropy field($H_k$) of 11 Oe. The amorphous $Co_{89}Nb{8.5}Zr{2.5}$ thin films annealed by rotational field annealing at $500^{\circ}C$ for one hour was found to be isotropy, and $4\piM_5$ of 0.9 T was obtained from these films, Also, the magnetic anisotropy of as-deposited films could be controlled by uniaxial field annealing at $400^{\circ}C$ for one hour. Anisotropy field($H_k$) of 17 Oe and $4\piM_5$ of 1.0 T were obtained by this method.

• 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 Magnetics
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• v.19 no.2
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• pp.121-125
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• 2014

$CoFe_2O_4(CFO)/BaTiO_3(BTO)/CoFe_2O_4(CFO)$ multilayered thin films were deposited on $Pt/TiO_2/SiO_2/Si$ substrates by the pulsed laser deposition (PLD) system with KrF excimer laser (${\lambda}=248nm$). BTO, CFO, BTO/CFO and CFO/BTO/CFO structured thin films were prepared and their crystal structures and microstructures, as well as their magnetic and magneto-electrical properties, were studied. The C-V characteristics of these multilayered thin films with different capacitor structures were obtained to confirm the change in their capacitances under a magnetic field. Finally, the capacitance of the CFO/BTO/CFO thin film as a function of bias voltage under an in-plane magnetic field of 1,000 Oe increased to 951.04 pF at 1 MHz, from 831.90 pF measured under no magnetic field, indicating 14.3% increase in magnetocapacitance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.29-29
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• 2008

Platinum Thin films were deposited on $Al_2O_3$ by Rf magnetic Sputtering. The physical and electrical characteristics of these films were analyzed under various deposition conditions(Ar gas pressure, input power, substrate temperature.) and annealing condition. The deposition rate was increased with increasing the input power but not increased linear. In the other factor, The Pt thin films property was associated with resistance. so lower resistance had more and more good Pt thin films condition. For the purpose of this study, we will get the best Pt thin film characteristics.

• Proceedings of the Korean Magnestics Society Conference
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• 1993.11a
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• pp.88-88
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• 1993

• Proceedings of the Korean Magnestics Society Conference
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• 1999.04a
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• pp.38-39
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• 1999