• Journal of the Korean Magnetics Society
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• v.3 no.1
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• pp.41-47
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• 1993

Effects of Ta addition on Co-Cr pependicular magnetic recording media were studied to obtain high perpen-dicular coercivity at lower substrate temperature. For the purpose. magnetic properties and microstructures of Co-Cr-(Ta) films were studied by varying the Cr contents from 17 to 21 at.% and Ta contents for 0 to 3.2 at.%. Effectiveness of Ta addition in increasing perpendicular coercivity was significant for lower Cr content films. The increasement of perpendicular coercivity was more pronounced for the films deposited on $100^{\circ}C$ heated substrate in the case of ${(Co_{83}Cr_{17})}_{98.4}Ta_{1.6}$ composition. The cause of the increase of perpendicular coercivity was considered due to not the grain refinement effects and the improvement of c-axis alignments but increase of Ta and Cr segregation.

• Journal of the Korean Magnetics Society
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• v.3 no.4
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• pp.314-319
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• 1993

The Effects of additional element X (X = Si, Mo, Cu, Gd) on magnetic properties and microstructure of Co-1Zat%Cr-Zat%Ta/Cr-X magnetic thin film were investigated. The thickness changes of Cr-X underlayer and CoCrTa magnetic layer were in the range of $1000~2000\AA$ and $200~800\AA$. respectively. Substrate temperatures were controlled from $100^{\circ}C$ to $200^{\circ}C$. Increase of coercivity by about 100~200 Oe was observed in CoCrTa/Cr-X thin films compared to those without additional X element. Cu was the most effective additional element for increasing coercivity. CoCrTa/Cr-Cu thin film shows relatively high coercivity in $1500\AA$ underlayer thickness and $600\AA$ magnetic layer thickness.

• Journal of the Korean Magnetics Society
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• v.3 no.3
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• pp.208-214
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• 1993

In order to investigate the origin of an increase in the coercivity with the Ta addition to Co-Cr films, the perpendicular magnetic anisotropy of Co-Cr film and CoCrTa film was measured by a torque magnetometer and VSM. In Co-Cr binary alloy film, the uniaxial anisotropy increased with increasing Cr content. The perpendicular magnetic anisotropy of $Co_{81.7}Cr_{16.7}Ta_{1.6}$ film was larger than that of $Co_{81}Cr_{19}$ film, both of which were deposited at the same substrate temperature of $100^{\circ}C$. The change in the perpendicular magnetic anisotropy with annealing was studied to understand the Ta addition effect. The amount of decrease in perpendicular magnetic anisotropy of the CoCrTa film by the annealing was larger than that of Co-Cr film. And the perpendicular magnetic anisotripies of Co-Cr film and CoCrTa film after annealing were almost the same. The cause of this was interpretated as the enhanced segregation of solute atoms in the Ta added thin film in the as-deposited state. The enhanced segregation of solute atoms increases the perpendicular magnetic anisotropy of the film, and causes the increase of perpendicular coercivity of the film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.578-581
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• 1999

The Co-Cr-Ta films are one of the most suitable candidates for perpendicular magnetic recording media. The facing targets sputtering(FTS) system has a advantage of preparing films over a wide range of working gas pressure on plasma-free substrates. In this study, we investigated the effect underlayers on the growths layers of Co-Cr-Ta recording layers. The Co-Cr-Ta/Ti(CoCr) double layers were deposited with sputter gas pressure$(P_N, 0.3-1mTorr)$ by using FTS apparatus at temperature of$40^{\circ}C~-300^{\circ}C$, respectively. Crystallographic and magnetic characteristics were evaluated by x-ray diffractometry(XRD) and vibrating sample magnetometer(VSM), respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.77-80
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• 2001

Crystallographic and magnetic characteristics of CoCr-based magnetic thin film for perpendicular magnetic recording media were influenced on preparing conditions. In these, there is that substrate temperature was parameter that increases perpendicular coercivity of CoCrTa magnetic layer using recording layer. While preparation of CoCr-based doublelayer, by optimizing substrate temperature, we expect to increase perpendicular anisotropy of CoCr magnetic layer and prepare ferromagnetic recording layer with a good quality by epitaxial growth. CoCrTa/Si doublelayer showed a good dispersion angle of c-axis orientation $\Delta$$\theta$$_{50}$ caused by inserting amorphous Si underlayer which prepared at underlayer substrate temperature 250C. Perpendicular coercivity was constant, in-plane coercivity was controlled a low value about 2000e. This result implied that Si underlayer could restrain growth of initial layer of CoCrTa thin film, which showed bad magnetic properties effectively without participating magnetization patterns of magnetic layer. In case of CoCrTa/Si that prepared with ultra thin underlayer, crystalline orientation of CoCrTa was improved rather underlayer thickness 1nm, it was expected that amorphous Si layer played a important role in not only underlayer but also seed layer.t also seed layer.r.

• Journal of the Korean Vacuum Society
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• v.3 no.2
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• pp.190-197
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• 1994

본 연구에서는 DC magnetron 스퍼터링법을 이용하여 고정밀, 고저항 저항체 박막으로 TaNx film을 제조하였을 때 형성될 수 있는 화합물 중 TaN0.1, TaN0.8과 TaN 박막의 Rs와 TCR특성을 평가하 고 film층의 우선방향성을 XRD를 이용하여 판명한 뒤 저항체의 Rs와 TCR에 미치는 영향을 조사하였 다. TaN0.1 박막이 35$\Omega$/$\square$의 면저항값과 안정된 TCR값을 나타내는 것을 알수 있었다. 두께50~200nm 의 TaN0.1과 Alumina 기판 사이에 정(+)의 TCR을 갖는 약 50nm의 Cr층을 증착하였을 때 Rs는 180$\Omega$/ $\square$ 과 TCR는 20ppm/$^{\circ}C$인 적층박막을 제조할 수 있었다. TaN0.1, TaN0.8 과 TaN 시편에서 화합물 형성 에 따른 Ta의 결합에너지를 ESCA를 이용하여 조사하였다. 이상의 연구결과로부터 TaN0.1 film이 TaNfilm 보다 고정밀, 고저항 박막 저항체 제조에 있어 우수한 전기저항 특성을 가지며 Cr 중간층 형성 으로 TCR이 $\pm$ppm/$^{\circ}C$정도로 안정된 고정밀 다층 저항체 박막을 형성할 수 있었다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.2
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• pp.148-153
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• 2004

The Hessian fly, Mayetiola destructor (Say), is known to be one of the major insect herbivores of wheat worldwide. In order to provide molecular events on interactions of the NIL with H21 and larvae of Hessian fly biotype L, the TaCR1 gene, Triticum aestivum cytokinin repressed 1, was isolated through the suppression subtractive hybridization, which was constructed using stems of the NIL with H21 at 6 days after infestation as tester and stems of the recurrent parent Coker797 without H21 at 6 days after infestation as driver. Transcript levels of TaCR1 mRNA in the NIL with H21 were highest at 6 days after infestation but in the Coker797 without H21 until 8 days were similar with those of non-infested plants. Expression of the TaCR1 gene was decreased at early time and then recovered after wounding or $H_2O$$_2$ treatment as well as 6-BAP treatment. Transcripts levels of the TaCR1 gene was changed after MeJA, SA, ethephone, or ABA treatment. In drought treatment, the TaCRl gene were increased at early stage of stress and then decreased at late stage. Expression of the TaCRl gene was continued to decrease through 24 h in the cold treatment. Although the TaCRl gene is increased through infestation in NIL with H21, further study was required to elucidate a role on resistance against larvae of Hessian fly. However, the TaCR1 gene could be used as marker gene on response of plants against abiotic stresses as well as application of plants with several hormones.

• Journal of Industrial Technology
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• v.21 no.A
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• pp.221-229
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• 2001

The effect of Mo underlayer on the magnetic properties of CoCrTa/Cr films deposited on glass substrates were investigated. The coercivity increased and the coercivity squareness decreased by introducing Mo underlayer. The coercivity increase was attributed to the increase of in-plane c-axis orientation and magnetic isolation of Co grains deposited on Cr/Mo underlayer. The decrease of coercivity squarenesses seemed to be caused by the increase of magnetic isolation. The increase of magnetic isolation of Co grains was attributed to the diffusion of Mo atoms into grain boundaries of Co films and the physical isolation of Co grains. The coercivity of CoCrTa/Cr/Mo showed maximum values at Mo thickness of $400{\AA}$. The appearance of the maximum coercivity at that thickness was attributed to the development of strong $Co(10{\bar{1}}0)$ and $Co(10{\bar{1}}1)$ preferred orientation.

• Journal of the Korean Vacuum Society
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• v.6 no.1
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• pp.77-84
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• 1997

Super precision resistor was manufactured by controlling properly the thickness of $TaN_{0.1}$ (negative TCR) and Cr(positive TCR) deposited on cylindrical alumina substrate (diameter: 4 mm, length: 11 mm). Multilayer thin film resistor of $Ta_2O_5/TaN_{0.1}$/Cr/Alumina (substrate) was manufactured by depositing of $Ta_2N_5$ film on $TaN_{0.1}$ film to increase Rs to the level of 1;k{\Omega}/{\box}$ and to passivate the film. Super precision resistor with TCR of $20\pm5 ppm/^{\circ}C$ and Rs of $1\;k{\Omega}/{\box}$ was manufactured by depositing thin layers of about 10 nm $Ta_2O_5$, 100 nm $TaN_{0.1}$ and 50 nm Cr film under the properly controlled sputtering condition.

• Proceedings of the Korean Vacuum Society Conference
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• 1993.07a
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• pp.87-88
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• 1993