• Journal of Korean Vacuum Science & Technology
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• v.5 no.2
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• pp.43-46
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• 2001

Fe-Au alloys are characterized by the complete solubility, and exhibit an fcc-bcc structural transformation at the Fe-rich side. The magneto-optical(equatorial Ken effect : EKE) and optical properties of Fe$\_$1-x/Aux (0 < x < 1) were investigated in the 0.5 - 5.0 eV energy range. The x-ray diffraction study shows the structural fcc-bcc transformation about 80 at. % of Fe. Noticeable changes in the optical properties caused by the fcc-bcc structural transformation was observed. The shape and intensity of the EKE spectra as well as the field dependence of the magneto-optical response were also significantly changed. It is thought that these changes are mainly comes from the induced magnetic moment in Au(and/or the emhanced magnetic moment of Fe). The nature of the prominent structure observed in the UV range of the magneto-optical Ken effect of Au/Fe multilayered films are disscussed in connection with the above results.

• Journal of Magnetics
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• v.8 no.1
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• pp.45-49
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• 2003

We present a brief review of recent experimental and theoretical results on new magneto-optical phenomena in magnetic granular metal-insulator alloys with tunnel-type magnetoresistance, focusing on magnetorefractive effect and cubic nonlinear magneto-optics.

• 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.

• The Korean Journal of Ceramics
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• v.6 no.4
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• pp.408-411
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• 2000

Although the rotation angle and its spectrum of the magneto-optical Kerr effect are physical quantities determined inherently by the material itself, we found that they can widely be designed by utilizing a one-dimensional photonic crystal with a ferromagnetic defect layer. By suitable choice of the film structure, the rotation angle at a designated narrow wavelength is resonantly enhanced up to as several hundred times larger as ordinary rotation angle of the magnetic. This is originated by the localization of light at the magnetic layer inside the film.

• Journal of Mechanical Science and Technology
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• v.14 no.10
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• pp.1072-1080
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• 2000

Leakage magnetic flux (LMF) is widely used for non-contact detection of cracks. The combination of optics and LMF offers advantages such as real time inspection, elimination of electrical noise, high spatial resolution, etc. This paper describes a new nondestructive evaluation method based on an original magneto-optical inspection system, which uses a magneto-optical sensor, LMF, and an improved magnetization method. The improved magnetization method has the following characteristics: high observation sensitivity, independence of the crack orientation, and precise transcription of the geometry of a complex crack. The use of vertical magnetization enables the visualization of the length and width of a crack. The inspection system provides the images of the crack, and shows a possibility for the computation of its depth.

• Journal of Magnetics
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• v.13 no.2
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• pp.70-75
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• 2008

In this study, a MOKE (Magneto-optical Kerr effect) measurement method for magnetic nanostructures is proposed. Theoretically, the MOKE signal enhancement can be predicted and confirmed when an anti-reflection coated substrate is used. Since MOKE is a ratio of reflectivity and the difference between the reflectivities for two magnetic states, when the reflectivity of the substrate part is reduced by employing an anti-reflection coated substrate, MOKE signal enhancement can be achieved. The enhancement is confirmed by simple numerical MOKE calculations. When the reflectivity of an anti-reflection coated substrate is 0.7%, the calculated MOKE signal is about 79% of its bulk values for the 100-nm wide Fe nanowire with a 1500-nm radius laser beam. It was found that, for various numerical calculations, a larger MOKE signal is obtained relative to a smaller substrate reflectivity.

• Journal of Magnetics
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• v.14 no.1
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• pp.31-35
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• 2009

Herein, the Magneto-Optical Kerr Effect (MOKE) signal enhancement in nanostructures in investigated. It is well known that the MOKE signals of ferromagnetic thin films are enhanced with an additional dielectric layer due to multiple reflections. The MOKE signal is modulated with the additional dielectric layer thickness and is at a maximum when reflectivity is at a minimum. This is not always true in the nanostructures due to the contribution from the non-magnetic substrate portion, especially when substrate reflectivity is minimized and the dependence of the additional dielectric layer thickness for the nanostructure is changed in the case of the continuous thin film. We showed that the MOKE signal for nanostructures could be enhanced with a properly designed, dielectric layer in addition to the anti-reflection coated substrates.

• Journal of the Korean Magnetics Society
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• v.4 no.4
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• pp.307-312
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• 1994

The magneto-optical Kerr effect due to the (Fe,Co)/(Pd,Pt,Cu,Ag) multilayer film is calculated considering of multiple reflection effect, and the calculated Kerr spectrum is compared to the reported experimental value. In case of Co/Pd, the reliance of composition and the variable tendency of magneto-optical Kerr rotation angle for Co thickness fully coresponds to experimantal and theoretical value. The theoretical Kerr spectrum of Fe/Cu and Fe/Ag multilayer films show the peaks near the Cu and Ag optical ansorption band in accordance with the experiment. But in case of Co/Pt, the increase tendency of Kerr rofation with decreasing wavelength reported by experiments could not be explained by the optical multiple interference. This difference of theoretical and experimental Kerr spectrum of Co/Pt film might be related with the change of electronic structure of Co and/or Pt from their bulk state.

• Current Optics and Photonics
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• v.4 no.2
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• pp.134-140
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• 2020

A significant enhancement of the magneto-optical Faraday rotation and extraordinary optical transmission (EOT) in the cascaded double-fishnet (CDF) structure with periodic rectangular apertures is theoretically predicted by using the extended finite difference time domain (FDTD) method. The results demonstrate that the transmittance spectrum of the CDF structure has two EOT resonant peaks in a broad spectrum spanning visible to near-infrared wavebands, one of them coinciding with the enhanced Faraday rotation and large figure of merit (FOM) at the same wavelength. It is most important that the resonant position and intensity of the transmittance, Faraday rotation and FOM can be simply tailored by adjusting the incident wavelength, the thickness of the magnetic layer, and the offset between two metallic rectangular apertures, etc. Furthermore, the intrinsic physical mechanism of the resonance characteristics of the transmittance and Faraday rotation is thoroughly studied by investigating the electromagnetic field distributions at the location of resonance. It is shown that the transmittance resonance is mainly determined by different hybrid modes of surface plasmons (SPs) and plasmonic electromagnetically induced transparency (EIT) behavior, and the enhancement of Faraday rotation is mostly governed by the plasmonic electromagnetically induced absorption (EIA) behavior and the conversion of the transverse magnetic (TM) mode and transverse electric (TE) mode in the magnetic dielectric layer.

• 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.