• 한국자기학회지
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• 제18권6호
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• pp.232-236
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• 2008

[CoFe/Pt/CoFe]/IrMn 다층박막에 대하여 반강자성체 IrMn층 두께 의존성 및 열적안정성, 수평으로 전환하는 각도에 의존하는 수직자기 이방성 특성을 관찰하였다. IrMn층을 통해 유도된 강자성체/비자성체/강자성체 구조인 [CoFe($10{\AA}$)/Pt($8{\AA}$)/CoFe($10{\AA}$)]/IrMn 다층박막은 IrMn 두께 $7{\AA}$부터 상호교환결합력이 형성되었고, 열처리 온도 $250^{\circ}C$까지 열적안정성을 유지하였다. 수직자기 이방성 [CoFe/Pt/CoFe]/IrMn 다층박막에서 바닥 CoFe층과 Pt층을 사이에 두고 반강자성체인 IrMn층에 의해 고정되어 있는 상부 CoFe층간의 상호교환결합력은 이방성 측정 각도가 $0^{\circ}$, $60^{\circ}$일 때 각각 1,000 Oe, 1,500 Oe로, $90^{\circ}$일 때 $\infty$ Oe로 나타났다.

• 한국전기전자재료학회논문지
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• 제17권8호
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• pp.888-892
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• 2004

It is necessary to develop soft magnetic layer with high saturation magnetization 4 $\pi{M}_s$ and in-plane magnetic anisotropy field Hk for soft magnetic underlayer of perpendicular magnetic recording media with high signal to noise ratio. Fe-Co-B layer with high 4 $\pi$Ms of about 23 kG deposited on Ni-Fe and Ni-Fe/Si seedlayer exhibited very high in-plane magnetic anisotropy filed Hk of about 280 and 380 Oe, respectively, In-plane XRD studies clarified that the lattice spacing of planes along the easy axis direction was longer than that along the hard axis direction in the Fe-Co-B layers with high Hk. These results indicate that high Hk of Fe-Co-B/Ni-Fe and Fe-Co-B/［Ni-Fe/si］ layers were resulted from magnetoelastic anisotropy owing to a residual stress. Moreover, the high Hk in the Fe-Co-B/Ni-Fe layer was maintained until 30$0^{\circ}C$ annealing temperature.

• Elastomers and Composites
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• 제36권1호
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• pp.30-36
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• 2001

이 연구의 목적은 카본블랙이 충전된 천연고무에서 비 등방성 발생에 영향을 주는 인자를 조사하기 위함이다. 고분자 사슬의 방향성은 인장특성에 영향을 준다. Pre-strained 방향의 parallel 시편은 등방성 혹은 perpendicular 시편에 비하여 낮은 인장영역에서 낮은 강도를 보이지만 높은 신장영역에서 높은 강도를 보인다. 고 인장 영역에서 parallel한 천연고무 시편은 비결정성인 SBR에 비하여 높은 강도를 보여주고 있다. 이것은 parallel 시편의 방향성에 영향을 받는 것으로, 시편의 방향성은 2차 인장시 결정화를 위한 핵으로 작용하여 결정화도를 증가시키는 것으로 보인다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.463-465
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• 2002

In order to increase perpendicular magnetic anisotropy of magnetic layer and prepare magnetic recording layer with a good quality by epitaxial growth between magnetic layer and, we prepared Co$\_$77/Cr$\_$20/Ta$_3$/Si doublelayer for perpendicular magnetic recording media which was promoted as next generation recording media on slide glass substrate. The thickness of magnetic layer and Underlayer were varied from 20 to 100 nm and 5 to 100 m, respectively. The surface morphology and crystal structure of the CoCrTa/Si film were examined with XRD and AFM. Prepared thin films showed improvement of dispersion angle of c-axis orientation Δ$\theta$$\_$50/ caused by inserting amorphous Si underlayer.

• Journal of Magnetics
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• 제14권4호
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• pp.144-146
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• 2009

This study examined the structure and perpendicular magnetization of FePt films grown on Pt/Fe/MgO(100) buffered Si(100) substrates by molecular beam epitaxy. The [Fe(0.17nm)/Pt(0.2nm)]$_N$ multilayers were prepared at room temperature to form a $L1_0$-FePt phase after vacuum annealing. Perpendicular magnetic anisotropy (PMA) was observed in the films after at least 15 repetitions (N = 15) of Fe/Pt deposition and annealing at $300{^{\circ}C}$ for 1 hour. Careful structural analysis of the films was carried out by x-ray diffraction and high-resolution transmission electron microscopy. These results will assist in the development of the low temperature $L1_0$- FePt deposition process, which will be essential for future extremely high density magnetic recording media.

• 한국표면공학회지
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• 제23권3호
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• pp.150-159
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• 1990

The magnetic properties of electrodeposited iron and cobalt films on porous aluminum oxide film were examined. There exists perpendicular magnetic anisotropy due to the shape anisotropy. The coercivity and squareness ratio of films were strongly dependent on deposited particle diameter. The effect of packing fraction on squareness ratio was also apprecible. Unlike the iron-deposited films, the magnetic properties of cobalt films were changed by preferred orientation because of it's large crystal ansotropy constant.(about 10 times of Fe) The Fe deposited films were found to be more suitable for perpendicular magenetic recording media bacause perpendicular coercivity, squareness ratio and the ratio of perpendicular coercivity to horizontal ones of iron films are greater than those of cobalt films.

• 자원환경지질
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• 제30권4호
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• pp.353-362
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• 1997

P wave velocities of core samples from the Pocheon granite were measured before and after applications of cyclic loading. Then. distribution of the pre-existing microcracks and microcracks developed due to the cyclic loading was investigated by analyzing P wave velocity anisotropies and microscopic observations from thin sections. Anisotropy constants were calculated with three different ways: (1) $C_A$ between the maximum and the minimum velocities, (2) $C_AI$ between velocities measured along the axial direction and the average of six velocities measured in the planes perpendicular to the loading axis (rift plane) and (3) $C_AII$ between the maximum and the minimum velocities measured in the plane perpendicular to the loading axis. Among anisotropy constants. $C_AI$ was the most effective anisotropy constant to identify the rift plane whose orientation is parallel to the pre-existing microcracks as well as the distribution of stress induced microcracks. $C_AI$ decreased after cyclic loading and the relationship between $C_AI$ and number of cycles shows comparatively coherent negative trends. indicating that stress induced microcracks are aligned perpendicular to the orientation of pre-existing microcracks and that the amounts are proportional to the number of loading cycles. The difference of anisotropy constants before and after cyclic loading was effective in delineating the level of cracks and we called it Induced Crack Index. Velocity measurements and microscopic observations show that anisotropy was caused mainly due to microcracks aligned to a particular direction.

• 한국자기학회지
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• 제6권3호
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• pp.158-164
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• 1996

동시진공증착으로 제조한 Tb/Co 조성변조 다층박막의 자기적 성질 및 광자기적 성질을 Tb의 두께 및 Tb/Co 각 층의 두께 비에 대하여 연구하였으며 열처리시 자기적 거동의 변화를 분석하였다. Tb의 두께가 $12{\AA}$일 때가 가장 큰 범위에서 수직자기이방성을 보였고, 최고 $6.52{\times}10^{6}erg/cc$의 수직자기이방성 에너지 값을 얻었다. Tb의 두께가 $12{\AA}$에서 최대 수직자기이방성을 보이는 것은 Tb/Co 계면에서의 Tb-Co이종 원자쌍뿐만 아니라 Tb-Tb, Co-Co 동종 원자쌍도 수직자기이방성에 기여하기 때문으로 사려된다. Kerr 회전각$({\theta}_k)$은 수직자기이방성 에너지$(K_{u})$와 비례, 평균 스핀분산각$(\alpha)$과는 반비례하는 거동을 보였으며 Tb두께 $12{\AA}$, 두께비 1.55에서 최대 Kerr 회전각 $0.28^{\circ}$를 얻었다. 열처리시 나타나는 비정상적인 이력곡선은 Tb층의 우선적인 산화로 Tb의 유효조성이 감소하여 조성이 보상점 근처로 이동하게 되어 Co층과의 보자력 차이가 커져서 나타난다.

• Journal of Magnetics
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• 제13권4호
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• pp.153-156
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• 2008

We conducted a micromagnetic modeling study to investigate the spin torque oscillator (STO) using a perpendicular polarizer. We used an additional layer of negative anisotropy constant materials (NAM) on a conventional STO. For the NAM layer, the magnetic easy plane is parallel to the in-plane easy axis of the free layer, and inhibits the development of the out-of-plane component of the magnetization in the free layer. As a result, this new type of STO provides a high frequency limit up to 50 GHz.

• Journal of Magnetics
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• 제13권4호
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• pp.160-162
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• 2008

In this work the magnetic anisotropies of magnetostriction material $Tb(Fe_{0.55}Co_{0.45})_{1.5}$ (named a-TerfecoHan) films were investigated with respect to working pressures in the range 1-7 mTorr. The results obtained show that perpendicular magnetic anisotropy (PMA) can be obtained at a working pressure above 5.1 mTorr. XRD was utilized to clarify the origin of the PMA observed in $Tb(Fe_{0.55}Co_{0.45})_{1.5}$ films, and revealed that all samples were amorphous. Therefore, we propose that the PMA effect is explained by stress produced in film due to internal relaxation process and magnetic anisotropy enhancements caused by magnetoelastic interactions.