• Journal of Magnetics
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• v.11 no.2
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• pp.77-82
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• 2006

The structure and magnetic properties of Fe-Ni films, deposited by DC magnetron sputtering on Si(111) wafer, have been studied. The spin wave stiffness constant is determined by Brillouin light scattering (BLS) and compared with the value obtained from magnetization measurements. The range of exchange interaction was determined as 0.4 atomic distances in the film deposited in a bias magnetic field, which is 1/2 that in the film grown in no bias magnetic field. The results show that the dimensions of exchange coupling increased by the sputtering in the magnetic field.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.3 s.32
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• pp.31-36
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• 2004

We charaterized electromagnetic shielding properties of a soft magnetic film using by a ASTM method and 2-port flanged coaxial line method in a RF range and quantitatively analyzed factors for the shielding effectiveness of the soft magnetic film in far field. The shielding effectiveness of the soft magnetic film was dominantly affected by absorption loss not reflection loss in high frequency range of 4-13.5 GHz.

• Korean Journal of Materials Research
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• v.28 no.3
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• pp.159-165
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• 2018

In order to increase the efficiency of the sputtering method widely used in thin film fabrication, a dc sputtering apparatus which supplies both high frequency and magnetic field from the outside was fabricated, and cobalt thin film was fabricated using this apparatus. The apparatus can independently control the applied voltage, the target-substrate distance, and the target current, which are important parameters in the sputtering method, so that a stable glow discharge is obtained even at a low gas pressure of $10^{-3}$ Torr. The fabrication conditions using the sputtering method were mainly performed in $Ar+O_2$ mixed gas containing about 0.6 % oxygen gas under various Ar gas pressures of 1 to 30 mTorr. The microstructure of Co thin films deposited using this apparatus was examined by electron diffraction pattern and X-ray techniques. The magnetic properties were investigated by measuring the magnetization curves. The microstructure and magnetic properties of Co thin films depend on the discharge gas pressure. The thin film fabricated at high gas pressure showed a columnar structure containing a large amount of the third phase in the boundary region and the thin film formed at low gas pressure showed little or no columnar structure. The coercivity in the plane was slightly larger than that in the latter case.

• Journal of Magnetics
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• v.12 no.1
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• pp.21-26
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• 2007

Si-based electromagnetic noise suppressors on coplanar waveguide transmission lines incorporated with a $SiO_2$ dielectric layer and a nanogranular Co-Fe-Al-O magnetic thin film are reported. Unlike glass-based devices, large signal attenuation is observed even in the bare structure without coating the magnetic thin film. Much larger signal attenuation is achieved in fully integrated devices. The transmission scattering parameter ($S_{21}$) is as small as -90 dB at 20 GHz at the following device dimensions; the thicknesses of the $SiO_2$ and Co-Fe-Al-O thin films are 0.1 $\mu$m and 1 $\mu$m, respectively, the length of the transmission line is 15 mm, and the width of the magnetic thin film is 2000 $\mu$m. In all cases, the reflection scattering parameter ($S_{11}$) is below -10 dB over the whole frequency band. Additional distributed capacitance formed by the Cu transmission line/$SiO_2$/Si substrate is responsible for these characteristics. It is considered that the present noise suppressors based on the Si substrate are a first important step to the realization of MMIC noise suppressors.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.710-715
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• 1995

Magnetic domains were observed using an image lock-in technique for backscattered electron contrast (Type II) with a 200 kV scanning electron microscope. Backscattered electrons indicate a difference in magnetic domain structures at the upper and lower parts of the upper pole in thin-film heads, changing the acceleration voltage. With this method, it is also possible to observe the domain structure of the thin-film head pole through a 10 to $20\;\mu\textrm{m}$ protective layer, and the upper shield of the MR head through the coil in the resist, alumina overcoat, and upper pole.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.591-598
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• 2002

Leakage magnetic flux is occurred in the cracked area of magnetized specimens, and also it changes the magnetic domain area of the magneto-optical film positioned on the specimen. It causes the change of the optical permeability of the magnetic domain on the crack area. So crack images can be obtained easily using this principle. On the other hand, utilizing a laser in this method makes possible to perform a remote sensing by detecting the light intensity contrast between cracked area and normal area. This paper shows the application of non-destructive inspection system taking advantage of magneto-optical method for micro-cracks and presents examples applied to the several types of specimens having fatigue cracks and fabricated cracks using this method. Also the authors prove the possibility of this method as a remote sensing system under the oscillation load considering application to real fields.

• Journal of the Korean institute of surface engineering
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• v.44 no.6
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• pp.255-259
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• 2011

The thickness dependence of magnetic properties was experimentally investigated in nanocrystalline Fe-Hf-N thin films fabricated by a RF magnetron sputtering method. In order to investigate the thickness effect on their magnetic properties, the films are prepared with different thickness ranges from 90 nm to 330 nm. It was revealed that the coercivity of the thin film increased with film thickness. On the contrary, the saturation magnetization decreased with film thickness. On the basis of the SEM and TEM, an amorphous phase forms during initial growth stage and it changes to crystalline structure after heat treatment at $550^{\circ}C$. Nanocrystalline Fe-Hf-N particles are also generated.

• Electrical & Electronic Materials
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• v.10 no.8
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• pp.813-818
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• 1997

In this study the thin film air core and magnetic core inductors consisting of planar coil and/or CoNbZr amorphous magnetic layers on a Si substrate were fabricated as spiral type by using rf magnetron sputtering and wet etching methods. The etchant solution was achieved by iron chloride solution(17.5 mol%) mixed with HF (20 mol%) during 150 sec which etched Cu films and CoNbZr/Cu/CoNbZr multi-layer films. They were about 10${\mu}{\textrm}{m}$ of thickness and 10$\times$10 mm$^2$of size. The properties of thin film magnetic core inductor were 400 nH of Q value at 10 MHz and the resonance frequency was about 300 MHz.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.212-214
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• 1994

At recent time, superconducting technology makes it possible to develop various devices using strong magnetic fields. As increasing with devices using high magnetic fields, magnetic shielding technology is essential in order to get high efficiency. Therefore it is necessary to establish production method and clear characteristics of suitable shielding materials. Usually, ferromagnetic metal has been used for shielding of high magnetic fields up to the present time. Instead of heavy ferromagnetic metal, we can acquire better upgraded shielding system by using of very light superconducting thin film that has a perfect diamagnetism. We would like to study basic characteristics of NbTi thin film produced by RF sputtering, investigated morphology and crystal structure of NbTi thin film by SEM and XRD, identified superconductivity measuring by critical current.

• Journal of the Korean Magnetics Society
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• v.7 no.6
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• pp.314-320
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• 1997

We have observed the orientation behavior of acicular iron oxides in magnetic layer of the particular magnetic tape after magnetic paint was coated on polyester film. As results of the static orientation, orientation of iron oxides come to the maximum at the front and the back of orientation magnets, but it was a litter lower at the back than at the front, and it slowly decreases and come to the constant level after passing through the orientation magnets. In case of edge portion to be futher away from center in the coated film, the orientation of iron oxides in magnetic layer come to worse than that of the center. We think it is owing to the shape and the magnetic magnitude of orientation magnets. The results of the dynamic orientation are as follows. As the orientation of iron oxides in the particulated magnetic tape is higher, the output properties of tape come to better than ever. And the orientation of iron oxides can be changed by drying condition, as result, the output properties of tape can be also. Therefore we think the considrations of the design of orientation magnets and the control of drying condition are needed to improve output properties of the particulated magnetic tape.