• Electrical & Electronic Materials
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• v.11 no.10
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• pp.72-77
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• 1998

The effects of Al micro-bumps on the magnetic properties of CoCr(Pt)Ta/Cr films deposited on glass substrates were investigated. The coercivity increased and the coercivity squareness decreased by incorporating Cr/Al underlayers. The cause of the coercivity increase is attributed to the reduction of Co(0002) texture, the increase of magnetic isolation of CoCr(Pt)/Ta grains, and the refinement of CoCr(Pt)/Ta grains deposited on Cr/Al underlayers. The effects of an Al overlayer on the magnetic properties of CoCr(Pt)Ta/Cr films were also studied. The decrease of coercivity squareness is ascribed to the magnetic isolation of CoCr(Pt)Ta grains.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.1
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• pp.17-22
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• 2000

A quaternary alloy film of $CoCr_{16.2}Pt_{10.8}Ta_4$was investigated for its magnetic properties and c-axis orientation with and without Ti underlayer. Additional elements such as Ta, Pt have been frequently introduced in CoCr alloy film for perpendicular recording as a means of improving magnetic performance. It has been reported that the addition of Pt and Ta in CoCr increase the coercivity and the magnetic isolation of columnar grains, respectively. However, CoCrPtTa perpendicular magnetic layer should be more increased its perpendicular magnetic anisotropy than at present for the application of ultrahigh recording density. The improvement of underlayers and substrate materials is one of the promised schemes to intensify the perpendicular magnetic anisotropy. In this study, the insertion of Ti underlayer shows the remarkable improvement of c-axis orientation compare with the direct deposition on the bare glass. The mechanism about this effect of Ti underlayer on CoCrPtTa is not to be clarified yet. Meanwhile, it is found that the magnetic domain of CoCrPtTa on 20 nm Ti underlayer has the continuous stripe pattern but the one of CoCrPtTa on 90 nm Ti underlayer shows the discrete mass type from the results of MFM investigation. This phenomenon is to be a distinct evidence that the improvement of perpendicular anisotropy by the adoption of Ti underlayer is originated from the reinforcement of the grain boundary segregation in CoCrPtTa alloy. Moreover, the transition of the M-H hysteresis pattern with the thickness of Ti underlayer indicates that the major contribution of Ti underlayer is not the magnetocrystalline anisotropy but the shape anisotropy due to the formation of uniform columnar grains by the nonmagnetic alloy segregation.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.350-351
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• 2000

• Journal of the Korean institute of surface engineering
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• v.37 no.4
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• pp.196-199
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• 2004

Seedlayers with low surface energy which increases the density of nucleation sites in the initial growth region of the recording layer deposited on them was studied to reduce grain size in recording layer. The seedlayer with low surface energy was so effective to attain finer grain in magnetic upper-layers. The Ni-Fe-O intermediate layer with low surface energy was found to be effective in reduction of grain size as well as magnetic cluster size of Co-Cr-Ta-Pt recording layer. Furthermore, the reduction of grain size in Co-Cr-Ta-Pt recording layer on Ni-Fe-O intermediate layer with low surface energy led to decrease the noise level in the high recording density region.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.182-183
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• 2002

고밀도 자기기록이 가능하기 위해서는 Ku가 크고 노이즈가 작은 매체가 필요하다. CoCrPt 기록층은 보자력이 크고 열적으로 안정하나 결정립크기가 크고 결정립간 교환 상호작용이 커서 노이즈가 크다.[1][2] 한편 CoCrPt 에 Ta, B 등 제4원소를 첨가하면 결정립이 크기가 감소하고 노이즈는 감소하나 Ku가 감소하여 열적으로 불안정해진다.[3] (중략)

• Journal of Magnetics
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• v.7 no.3
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• pp.115-125
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• 2002

We proposed a novel method to evaluate the magnetic properties of the initial layer and the columnar structure separately for CoCr-based perpendicular recording media. We show that the thickness of the initial layer and the intrinsic magnetocrystalline anisotropy of columnar structure can be quantitatively evaluated using the plotted product of perpendicular anisotropy to magnetic film thickness versus magnetic film thickness ($K_{u{\bot}}^{ex{p.}}$ $\times$ d$_{mag.}$ vs. d$_{mag.}$ plot). Based on the analyses, it is found that: (1) compared with CoCrPtTa media, CoCrPtB media have relatively thin initial layer, and have fine grains with homogeneous columnar structure with c-plane crystallographic orientation; (2) CoCrPtB media can be grown epitaxially on Ru or CoCr/C intermediate layer, and as the result, the magnetic properties of the media within thin thickness region of d$_{mag.}$ $\leq$ 20 nm is significantly improved; (3) the key issue of material investigation for CoCr-based perpendicular recording media will be focused on how to fabricate c-plane-oriented columnar grains well isolated with nonmagnetic substance in epitaxial-growth media, while maintaining the thermal stability of the media.

• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.245-252
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• 2011

콜롬비아는 안데스 산맥의 북단에 위치하며 NS 방향의 단층대를 기준으로 지질 환경의 차이가 크다. 단층대를 기준으로 동부지역은 원생대 변성암류와 이를 피복하는 고생대 변성퇴적암류가 주로 분포하며, 서부 지역은 고생대 퇴적암류, 중생대 화성암류, 제 3 기 화산양류 및 퇴적암류가 주로 분포한다. 지화학이상대는 6개 그룹으로 분류되며, 철 (Fe), 귀금속(Au, Ag, Pt), 기초금속(Cu, Pb, Zn), 희유금속(Sn, Cr, Co, Mn, Mo, Ni, Nb, W, V, Mg, Ti, Be, REE, Ga, Zr, Hf, Se, Te, Ta, Cd, In, Li 등) 빛 핵원료자원인 U 이상대로 구성된다. 콜롬비아의 주요 부존자원은 석탄, 니켈, 금 및 에메랄드이다. 에메랄드, 석탄 및 니켈은 세계적인 매장규모와 생산량을 보인다. 콜롬비아는 탐사가 거의 수행되지 않은 지역이 전 국토의 49%에 달해 광물부존 잠재성은 현재보다 크게 높을 것으로 보인다. 따라서 최근 콜롬비아와의 광물자원 협력이 강화되고 있는 시점에서 미탐사 지역을 대상한 공동탐사를 지화학 이상대가 확인된 지역을 중심으로 수행하여 신규광체를 확보하고, 광물자원 협력을 강화함으로써 공동개발 여건을 마련할 필요가 있다고 판단된다.