• Proceedings of the Korean Magnestics Society Conference
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• 1998.10a
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• pp.92-93
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• 1998

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.411-412
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• 2000

• Proceedings of the Korean Magnestics Society Conference
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• 1999.10a
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• pp.82-83
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• 1999

• Proceedings of the Korean Magnestics Society Conference
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• 1999.10a
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• pp.84-85
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• 1999

• Journal of Astronomy and Space Sciences
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• v.20 no.3
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• pp.185-196
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• 2003

In this paper, we make a design study for a local oscillator system of the 100 ㎓ band cosmic radio receiving system. We use the YIG oscillator with digital driver which is the main oscillator. This oscillator has a good frequency and phase stability at some temperature variation, and the easy computer aided control characteristics. This total system designed to two subsystem, first is the oscillator system include YIG oscillator, tripler, harmonic mixer and triplexer etc., second is the PLL system to supply the precise and stable local oscillator frequency to mixer. The proposed local oscillator system in this paper can be used in a single or multi pixel receiver because this system can be lock the local oscillator frequency automatically using PC.

• Journal of the Korean Ceramic Society
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• v.39 no.5
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• pp.498-502
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• 2002

Pure-yttrium iron garnet($Y_3Fe_5O_{12}$2, YIG) thick films were grown from a $PbO/B_2O_3$ flux onto (111) SGGG substrate using liquid phase epitaxy. The effect of substrate rotation speed and supercooling on crystallinity, chemical composition and growth rate of the thick films was investigated. The FWHM of films decreased with increasing of growth temperature from 860 to 910${\circ}C$. A substrate rotation speed of 120 rpm at 910${\circ}C$ lead to growth rates up to $60{\mu}m/h$.

• Korean Journal of Materials Research
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• v.25 no.12
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• pp.703-707
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• 2015

In this study, we investigated the effect of annealing conditions on the ferromagnetic resonance(FMR) of yttrium iron garnet ($Y_3Fe_5O_{12}$, YIG) thin film prepared on gadolinium gallium garnet ($Gd_3Ga_5O_{12}$, GGG) substrate. The YIG thin films were grown by rf magnetron sputtering at room temperature and were annealed at various temperatures from 700 to $1000^{\circ}C$. FMR characteristics of the YIG thin films were investigated with a coplanar waveguide FMR measurement system in a frequency range from 5 to 20 GHz. X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) were used to characterize the phase formation, crystal structure and composition of the YIG thin films. Field dependent magnetization curves at room temperature were obtained by using a vibrating sample magnetometer(VSM). The FMR measurements revealed that the resonance magnetic field was highly dependent on the annealing condition: the lowest FMR linewidth can be observed for the $800^{\circ}C$ annealed sample, which agrees with the VSM results. We also found that the Fe and O composition changes during the annealing process play important roles in the observed magnetic properties.

• Journal of the Korean Magnetics Society
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• v.9 no.2
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• pp.91-97
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• 1999

YIG $(Y_3Fe_5O_{12})$ films with 4~80 ${\mu}{\textrm}{m}$ thickness were epitaxially grown on GGG $(Gd_3Ga_5O_{12})$ substrates by LPE (liquid phase epitaxy) techniques. Using various melts having different chemical composition the growth temperature was varied as a parameter. Growth rate, surface morphology, chemical composition, lattice constant, saturation magnetization, and magnetic resonance of the films were investigated. Lattice mismatch between the substrate and film Δa, saturation magnetization, and magnetic resonance line width ΔH increased, decreased, and increased, respectively, as undercooling temperature ΔT increased. The films grown by using the melt with larger R$_1$and smaller R$_3$had smaller ΔH. The major origin of the increase of ΔH was the increase of Δa. It is considered that the magnetic field in the film became locally inhomogeneous with the increase of Δa due to the increase of inhomogenity in stress distribution to the film depth direction. Therefore, in order to grow YIG films with small microwave loss it is necessary to grow films at small ΔT using the melt with large R$_1$and small R$_3$resulting in a small Δa.

• Korean Journal of Materials Research
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• v.11 no.3
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• pp.203-206
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• 2001

The effects of SrTiO$_3$ addition and sintering temperature on the microstructure and magnetic properties of yttrium iron garnet (YIG) were investigated. The lattice Parameter increasing of sintered YlG with small amount of SrTiO$_3$ addition was supposed to be substituted $Y^{+3}$, Fe$^{+3}$ ions to Sr$^{+2}$,Ti$^{+4}$ ions which are relatively large in ionic ranius. A YIG specimen sintered at 142$0^{\circ}C$ with 0.2mol% SrTiO$_3$ showed above 98% densification of theoretical density. Saturation magnetization (M$_s$) at room temperature decreased a little bit with increasing SrTiO$_3$, addition but no great chance. In addition, the coercivity (H$_c$) was almost not changed by sintering temperature.

• Proceedings of the Korean Magnestics Society Conference
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• 1997.05a
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• pp.118-119
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• 1997