• Applied Microscopy
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• v.48 no.4
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• pp.128-129
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• 2018

Soft ferromagnetic materials are utilized for various electromagnetic devices such as magnetic recording heads and magnetic shielding. In situ observation of magnetic microstructures and domain wall motions are prerequisite for understanding and improving their magnetic properties. In this work, by the Fresnel (out-of-focus) method of Lorentz microscopy, we observe the domain wall motions of polycrystalline Ni/Ti thin film layers triggered by single-shot laser pulse. Random motions of domain walls were visualized at every single pulse.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.173.1-173.1
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• 2014

The variations of electronic and magnetic properties of ultrathin Fe overlayers on a W(001) surface as a function of Fe film thickness (1.0~4.0 ML) has been investigated using x-ray magnetic circular dichroism (XMCD) in conjunction with ultraviolet photoelectron spectroscopy (UPS) and low energy electron diffraction (LEED). We found that the ferromagnetic property of Fe film started to build up over 2.0 ML, as we confirmed the spin and angular moment contribution to the magnetic moment using XMCD experiments. We will systematically demonstrate that the occurrence of ferromagnetic property of Fe film on a W(001) surface is closely correlated to a themally stable layer of Fe film on a W(001) surface.

• Journal of Magnetics
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• v.10 no.3
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• pp.113-117
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• 2005

Some polycrystalline ferromagnetic mms are composed of continuously connected nanometer scale islands with random crystallite orientations. The nanometer perturbations of the mm introduce a large number of nearly degenerate local field configurations that are indistiguishable on a macroscopic scale. As a first step, this situation is modelled as a thin ferromagnetic disc coupled by exchange and dipole interactions to a homogeneous ferromagnetic plane, where the disc and plane have different easy axes. The model is solved to find the partial $N\acute{e}el$ domain walls that minimize the magnetic energy. The two solutions give a bistable configuration that, for appropriate geometries, provides an important microsopic ferromagnetic degree of freedom for the mm. These results are used to interpret recent measurements of exchange biased bilayer films.

• Journal of the Korean Magnetics Society
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• v.3 no.2
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• pp.125-129
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• 1993

The magnetic properties of RF magnetron sputtered $Co_{79}Cr_{21}(at.%)$ thin film have been examined by using of ferromagnetic resonance. The properties of $Co_{79}Cr_{21}$ thin film show the effective first order anisotropy constant of $2.91{\times}10^{5}\;erg/cm^{3}$, the effective anisotropy field of 2526 Oe, and the spectroscopic splitting factor of 2.17. The torque experimental results, analyzed by employing modified Artman method, coincide with the ferromagnetic res-onance experimental results.

• Journal of the Korean Ceramic Society
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• v.43 no.2 s.285
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• pp.74-78
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• 2006

A non-integrated type noise filter on a Coplanar Waveguide (CPW) transmission line is demonstrated by using a highly resistive $Co_{41}Fe_{38}Al_{13}O_8$ nanogranular thin film with the dimensions of $4\;mm (\iota)\times4\;mm(\omega)\times0.1\;{\mu}m(t)$. The noise suppression characteristics are evaluated without placing an insulating layer between the CPW line and the magnetic thin film. 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 power loss is very large and the degree of noise attenuation is measured to be 3 dB. This level of noise attenuation is still small for real applications; however, considering the small magnetic volume used in this work, further improvement is expected by simply increasing the magnetic volume and by integrating the magnetic thin film into the CPW transmission line.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.528-532
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• 1995

Ferromagnetic resonance experiments have been used to investigate the magnetic properties of amorphous $Co_{89.5}Zr_{10.5}$ thin films deposited by DC magnetron sputtering method. In the thickness range from $350\;{\AA}$ to $3,200\;{\AA}$, measurements were carried out in a static magnetic field perpendicular and parallel to the film plane and in a conventional 9.44 GHz spectrometer at room temperature. The ferromagnetic resonance spectra by the field perpendicular to the film plane showed standing spin wave. The spacing and the relative intensities between the various spin wave resonance peaks are analysed considering surface magnetic anisotropy. The surface magnetic anisotropy constant ($K_{so},\;K_{sd}$) of amorphous $Co_{89.5}Zr_{10.5}$ thin films are $0.02\;erg/\textrm{cm}^2$ and $0.55\;erg/\textrm{cm}^2$ respectively regardless of the film thickness except for $3,200\;{\AA}$ film. In case of $3,200\;{\AA}$ these values are $0.46\;erg/\textrm{cm}^2$ and $0.55\;erg/\textrm{cm}^2$ respectively.

• Journal of Magnetics
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• v.8 no.3
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• pp.103-107
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• 2003

Relaxation of magnon in a very thin ferromagnetic film through spontaneous emission of photon shows an enhancement of the decay rate due to the phase coherence between the magnon and the planar component of wave vector of photon. The coupling between magnon and photon under a strong external magnetic field is considered only at the lowest order one-magnon one-photon process, which we believe the most dominant channel for the radiation from the system. Theoretical understanding related to the geometric confinement is pursued; the phase coherence due to the crystal symmetry in the film plane gives rise to superradiative emission on one hand, but the symmetry breaking along the direction perpendicular to the film renders the possibility of emission itself, providing the increased degrees of freedom for the photon.

• Journal of Magnetics
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• v.18 no.2
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• pp.155-158
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• 2013

FeCoB films were being prepared on a Ru underlayer by using the oblique incidence of sputtered and back-scattered particles which have a high in-plane magnetic anisotropy field $H_k$ above 400 Oe. It is suitable to attain such deposition condition when facing targets sputtering system. The in-plane X-ray diffraction analysis clarified that there is anisotropic residual stress which is the origin of the high in-plane magnetic anisotropy. The directional crystalline alignment and inclination of crystallite growth were also observed. Such anisotropic crystalline structures may affect the anisotropic residual stress in the films. The B content of 5.6 at.% was appropriate to induce such anisotropic residual stress and $H_k$ of 410 Oe in this experiment. The film with B content of 6 at.% possessed large saturation magnetization of 22 kG and high $H_k$ of 500 Oe. The film exhibited high ferromagnetic resonance frequency of 9.2 GHz.

• Journal of the Korean Magnetics Society
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• v.14 no.4
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• pp.120-126
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• 2004

In order to understand the temperature dependence of magnetic properties of $F_{84}Nb_{16}$(wt.%) thin films, ferromagnetic resonance experiments have been carried out. The ferromagnetic resonance spectra for all temperatures consist of several volume modes and one (or two) surface modes. It is suggested that both surface of the film have a perpendicular hard axis to the film plane (negative surface magnetic anisotropy). Saturation magnetization coincides with the Block's T$\^$2/3/ and spectroscopic splitting factor is almost constant in the temperature range from 113 K to 293 K. The surface magnetic anisotropy constant K$\_$s2/ of the film-substrate interface increased with decreasing temperature in the temperature range from 233 K to 293 K. The surface magnetic anisotropy constant K$\_$s1/ of the air-substrate interface decreased from -0.322 erg/$\textrm{cm}^2$ to -0.394 erg/$\textrm{cm}^2$ as the temperature decreased to 253 K and was almost constant below 233 K.233 K.

• 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.