• Journal of the Korean Society for Precision Engineering
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• v.24 no.9
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• pp.95-102
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• 2007

The scanning electron microscope (SEM) is one of the most popular instruments available for the measurement and analysis of the micro/nano structures. It is equipped with an electron optical system that consists of an electron beam source, magnetic lenses, apertures, deflection coils, and a detector. The magnetic lenses playa role in refracting electron beams to obtain a focused spot using the magnetic field driven by an electric current from a coil. A SEM column usually contains two condenser lenses and an objective lens. The condenser lenses generate a magnetic field that forces the electron beams to form crossovers at desired locations. The objective lens then focuses the electron beams on the specimen. The present work concerns finite element analysis for the electron magnetic lenses so as to analyze their magnetic characteristics. To improve the performance of the magnetic lenses, the effect of the excitation current and pole-piece design on the amount of resulting magnetic fields and their peak locations are analyzed through the finite element analysis.

• Journal of the Korean institute of surface engineering
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• v.31 no.5
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• pp.261-265
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• 1998

We investigated compositional separation of Co-23%Cr magnetic alloy thin films with varying film thicknesses. Saturation magnetization and magnetic microstructures were investigated using vibrating sample magnetometer (VSM) and scanning probe microscope (SPM), respectively. Saturation magnetization was as 700 emu/cc for films below 50 nm-thick, and changed to 430 emu/cc for the ones above 2000 nm-thick. This may be due to increment of molar volume of Cr-enriched phase as film thickness increases. The surface grain size in AFM (atomic force microscope) measurement becomes larger as film thickness increases. The MFM (magnetic force microscope) reveals that magnetic microstructure is changed from the fine spherical domains to the maze type domains as film thickness increases. We conclude that employing thickness of Co-22%Cr films below 50 nm is favorable for high density recording in order to enhance perpendicular saturation magnetization and SNR (signal to noise ratio).

• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.12-12
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• 2007

• Journal of Magnetics
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• v.18 no.2
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• pp.188-191
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• 2013

The magnetic properties for sanal's mobility inside of the lymphatic primo vascular system, the so-called Kyungrak (or meridian) system, are investigated under a low static magnetic field with the anatomy technology and optical microscope. One sanal with a size of 1 ${\mu}m$ under microscope selected and separated from the primo vessels of the primo vascular system are observed in rabbits' lymphatic vessels around abdominal aorta and placed in PBS solution with petridish. The moving displacement of sanal versus the measuring time of 20 Oe below a magnetic field of 80 Oe is stronger in dominanting dependence according to the x-direction than y-direction.

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.59-59
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• 2004

• Journal of the Korean Magnetics Society
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• v.27 no.1
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• pp.35-40
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• 2017

Kerr microscopy was assembled to observe magnetic domain image of ultra thin 3 %Si-Fe by using parts of an optical microscope. Digital images were obtained from CCD camera attached to the microscopy. A method was suggested to decide a boundary between magnetic domain regions in this study. The method was using some operations such as subtraction, integration and least mean square approximation for pixel values in the digital image. The method has a strong point that high priced image processor is not needed in the Kerr microscopy system. From the results that three different domain walls were observed and magnetic flux density of 0.085 [T], this method could be applied in the magnetic domain regions having a straight $180^{\circ}$ domain wall.

• Journal of Magnetics
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• v.8 no.1
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• pp.13-17
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• 2003

The longitudinal magnetooptical Kerr effect was used to analyse magnetic domains in soft magnetic ${(Fe_{97}A1_3)}_{85}N_{15}$/$Al_{2}O_{3}$ multilayers in order to get microscopic understanding of interlayer exchange coupling. The measuring system consists of a Kerr microscope, a CCIR camera (with an 8-bit framegrabber), 16 bit digital camera and computer system for real-time image processing and to control external magnetic field and cameras. The strength of ferromagnetic (EM) coupling as a function of the spacer thickness of $Al_2O_3$ was investigated. It was found that strong FM-coupling, strong uniaxial anisotropy and coherent rotation of the magnetization have been observed for the spacer thickness in the range of 0.2 nm $\leq$ t $\leq$ 1 m, however, weak FM-coupling, patch domains and $360^{\circ}$-walls occur for the spacer thickness of t = 2.5 nm. At a spacer thickness of t $\geq$ 5 nm transition takes place from weak FM-coupling to the decoupled state where complex interlayer interactions and different types of the domain walls were observed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1017-1020
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• 2004

It is not efficient and scarcely out of the question to use commercial expensive electron beam lithography system widely used for semiconductor fabrication process for the manufacturing application field of various devices in the small business scope. Then scanning electron microscope based electron beam machining system is maybe regarded as a powerful model can be used for it simply. To get a complete suite of thus proper system, column unit build up with several electo-magnetic lens is necessarily required more than anything else to modify scanning electron microscope. In this study, various components included several electro-magnetic lens and main body which are essentially constructed for column unit are designed and manufactured. And this established column unit will be used for next connected study in the development step of scanning electron microscope based electron beam machining system.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.11
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• pp.92-98
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• 2009

The scanning electron microscope (SEM) contains an electron optical system in which electrons are emitted and moved to form a focused beam, and generates secondary electrons from the specimen surfaces, eventually making an image. The electron optical system usually contains two condenser lenses and an objective lens. The condenser lenses generate a magnetic field that forces the electron beams to form crossovers at desired locations. The objective lens then focuses the electron beams on the specimen. The present study covers the design and analysis of an objective lens for a thermionic SEM. A finite element (FE) analysis for the objective lens is performed to analyze its magnetic characteristics for various lens designs. Relevant beam trajectories are also investigated by tracing the ray path of the electron beams under the magnetic fields inside the objective lens.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.8
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• pp.744-751
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• 2003

Co-Pd alloy thin films prepared by a DC-sputter that have self-organized nano structure(SONS), are promising for high-density information storage media in information era. We prepared the samples by varying Pd contents of 0~8.1 wt% at the substrate temperatures of room temperature (RT) and 200 $^{\circ}C$, respectively Microstructure and Pd contents of the Co$_{1-x}$ Pd$_{x}$ films are probed by a scanning electron microscope (SEM), a transmission electron microscope (TEM) and an energy dispersive spectrometer (EDS). We also investigated the saturation magnetization (Ms), remanence and coercivity of the Co$_{1-x}$ Pd$_{x}$ films. Surface roughness are measured by an atomic force microscope (AFM). We revealed that self-organized nano size Co-enriched phase and Pd-enriched phase existed with Pd contents at the substrate temperatures of RT and 20$0^{\circ}C$ through microstructure characterization. SONS helped to keep the saturation magnetization and enhance the perpendicular anisotropy with Pd contents. Out result implies that we may tune the perpendicular magnetic properties with keeping the saturation magnetization by varying substrate temperatures and Pd contents for high density magnetic recording.rding.