• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.47-49
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• 1988

This paper discusses dynamic properties of bubble garnet thin films. The dynamic properties considered are Gilbert damping parameters, saturation velocity, and wall mobility. The parameters are evaluated to facilitate the search for desirable garnet thin film compositions. Given bubble diameter and Q-value, the computer prints out all compositions which meet the desired requirements. The computer model determines magnetization, anisotropy, damping, velocity, mobility among others from the film compositions. The computer modeling program is described by an algorithm detailing its operation.

• Journal of the Korean Magnetics Society
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• v.13 no.1
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• pp.36-40
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• 2003

We have grown D $y_{x}$B $i_{3-x}$F $e_{5}$ $O_{12}$ (x = 0.5,1.0, 1.5,2.0) magnetic garnet thin films upon $Al_2$O3i and GGG substrate using Pechini process. The annealing temperature to get single phase D $y_{x}$B $i_{3-x}$F $e_{5}$ $O_{12}$ garnet is dependent on substrate, i.e. the annealing temperature for GGG substrate il 5$0^{\circ}C$ lower than that for $Al_2$ $O_3$ substrate. The grains of garnet thin film grown on GGG (111) plane align along [111] direction, and in this case the hysteresis curve does not saturate up to H : 5000 Oe. We attribute this phenomenon to rotation magnetization process. The maximum amount of Bi substitution in polycrystalline D $y_{x}$B $i_{3-x}$F $e_{5}$ $O_{12}$ thin film prepared by Pechini process is restricted to 2.0 Bi atom/unit cell, and this value is less than that in single garnet crystall grown by LPE method.own by LPE method.ethod.

• 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.

• The Korean Journal of Ceramics
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• v.1 no.2
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• pp.91-95
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• 1995

Polycrystalline bismuth- and aluminum- substituted dysporsium and yttrium iron garnet (Bi2R3-xAlyFe5-yO12, R=Dy or Y, $0\leqx\leq3, \; 0\leqy\leq3$) films have been prepared by pyrolysis. The crystallization temperatures, the solubility limit of bismuth ions into the garnet phase, and magnetic and magneto-optic properties of the films have been investigated as a function of bismuth and aluminum concentration. It was found that the crystallization temperatures as a function of bismuth and aluminum concentration. It was found that the crystallization temperatures of these films rapidly decreased as bismuth concentration. It was found that the crystallization temperatures of these films rapidly decreased as bismuth concentration (x) increased up to x=1.5 and then remained temperatures of these films rapidly decreased as bismuth concentration (x) increased up to x=1.5 and then remained unchanged at x>1.5, whereas, showed no changes as aluminum concentration (y) increased up to y=1.0 and then gradually increased at y>1.0. The solubility limit of bismuth ions was x=1.8 when y=0 but increased to x=2.3 when y=1.0. It was demonstrated that the magnetic and magneto-optic properties of the dysprosium iron garnet films could be tailored by bismuth and aluminum substitution suitable for magneto-optic recording as follows. The saturation magnetization and coercivity data obtained for the films indicated that the film composition at which the magnetic compensation temperature became room temperature was y=1.2 when x=1.0. Near this composition the coercivity and the squareness of the magnetic hysteresis loop of the films were several kOe and unit, respectively. The Curie temperatures of the films increased with the increase of x but decreaed with the increase of y, and was 150-$250^{\circ}C$ when x=1.0 and y=0.6-1.4. The Faraday rotation at 633 nm of the films increased as x increased but decreased as y increased, and was 1 deg/$\mu\textrm{m}$ when x=1.0 and y=1.0. Based on the data obtained, the appropriate film composition for magneto-optic recording was estimated as near x=1.0 and y=1.0 or $BiDy_2AlFe_4O_{12}$.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.11
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• pp.69-76
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• 1990

To find out whether isotropic magnetic bubble propagation can be achived by changing magnetostriction coefficients, bias margins and bubble collapse fields of $2.5{\mu}m$ period "diamond" bubble propagation tracks were measured which were fabricated on three magnetic garnet thin films with nearly isotropic magnetostriction coefficients (${\lambda}111{\simeq}{\lambda}100$). The results showed substantially isotropic bubble propagation in "super","good" and "bad" tracks for all three garnet films. From the bubble collapse fields, the bubble potential well depths vs. the direction of the in-plane rotating magnetic fields were plotted. The results showed that substantial differances in the potential well shapes exist for the three "good," "bad" and "super" tracks when ${\Delta}(=({\lambda}111-{\lambda}100)/{\lambda}100)$ was 0.5 (film AK92). However, the differences were minimal when ${\Delta}$ were 0.3 (film Aka8) or 0.1 (film AKb1). In other words, the bubble potential wells were nearly isotropic. The above two measurements indicate that nearly isotropic bubble propagation can be achieved when B is between 0.1 and 0.3.

• Journal of Magnetics
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• v.11 no.3
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• pp.147-150
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• 2006

We have fabricated three-dimensional magnetophotonic crystals based on $\alpha$-$SiO_2$ opal films. Opal thin films grown on glass substrates were filled with bismuth substituted iron garnet (Bi:YIG). Scanning electron microscopy data, optical and magnetic properties of the synthesized samples confirm the presence of the Bi:YIG contentin the opal lattice. It is shown that the samples exhibit the (111) stop band, and transmissivity of the threedimensional magnetophotonic crystals is defined by both the film lattice and the Bi:YIG content.

• Journal of the Korean Magnetics Society
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• v.10 no.3
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• pp.123-132
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• 2000

Cerium substituted YIG thin films were grown by rf magnetron sputter techniques. We investigated the effects of post-deposition heat-treatment as well as various deposition parameters such as substrate materials, substrate temperature. sputter power, and sputter gas types on the crystallinity, chemical composition, microstructure and magnetic characteristics of the films. Post-deposition heat treatment over 750 $\^{C}$ was applied to crystallize as-prepared amorphous films, and a strong tendency of particular crystallographic planes tying parallel to substrate surface was observed for the post-deposition heat-treated films on GGG substrate. The chemical composition of the films exhibited a wide range of chemical stoichiometry depending on the oxygen fraction of sputter gas, and in particular the composition of the film deposited in sputter gas with an oxygen fraction of R = 10% was Ce$\_$0.23/Y$\_$1.30/Fe$\_$3.50/O$\_$12/. With raising the temperature of post-deposition heat-treatment from 900 $\^{C}$ to 1100 $\^{C}$, the surface roughness of the film on GGG substrates increased from about 3 nm to 40 nm, but their coercive force and ferromagnetic resonance line width decreased from 0.477 kA/m to 0.369 kA/m and from 12.5 kA/m to 8.36 kA/m, respectively.

• Journal of the Korean Magnetics Society
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• v.8 no.2
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• pp.74-78
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• 1998

High quality single cystal Bi, Gd : YIG films have been grown on GCMZGG wafers by LPE techniques. The magnetic, magneto-optic and sensor properties of the films have been investigated. The films showed high linearity with almost no hystersis, saturaton Faraday rotation angle of 45$^{\circ}$, saturation field of about 1.1 kOe, Verdet constant of 5.6$^{\circ}$ /(Oe, cm) at room temperature, and temperture coefficient of Verset constant of 0.0056$^{\circ}$ /(Oe, cm, $^{\circ}C$) in the range of 0 $^{\circ}C$~100 $^{\circ}C$. The sensor made out of the film exhibited highly linear signal in the range of 3 A-300 A.