• 한국자기학회지
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• 제4권3호
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• pp.256-262
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• 1994

코발트 단위층의 두께가 $2{\AA}$ 및 $4{\AA}$인 두 경우에 대해 막의 총두께가 약 $200{\AA}$인 Co/Pd 다층막을 제조하였으며 이 때 스퍼터링 압력이 자화반전 및 수직자기이방성에 미치는 영향에 대해 연구 하였다. 수직자기이방성 에너저지가 최대치를 보이는 압력이 존재하였으며 $2{\AA}$ 코발트층의 경우 $4{\AA}$ 경우 보다 낮은 압력에서 최대치가 나타났다. 자화시 자구벽 이동은 압력이 높을수록 어려워졌으며 높은 압력에서 는 자구벽 이동으로부터 자기모멘트 회전으로 자화반전기구가 바뀌었다. 또한 코발트층의 두께가 $2{\AA}$인 경우가 $4{\AA}$인 경우보다 수직자기이방성 에너지가 큰 것으로 나타났다.

• Macromolecular Research
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• 제8권6호
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• pp.268-275
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• 2000

After imposing a large pre-strain, anisotropy increases with increasing residual extension ratio. Gums have very low residual extension ratio and exhibit little anisotropy, while black filled SBR and especially sulfur-cured carbon black filled NR have large set and anisotropy. For carbon black filled rubber, samples subjected to tensile loading in perpendicular to the pre-strain direction have the same stress-strain curves shape as the sample without pre-strain (=isotropic samples), but slightly lower modulus. However, compared to isotropic or perpendicular directional samples to pre-strain direction, samples subjected to tensile loading in parallel to the pre-strain direction show low stress at low deformation, but have high stiffness at high deformation. Normalized anisotropy changes with strain. The normalized anisotropy for various deformations is a linear function of residual extension ratio.

• Journal of Magnetics
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• 제10권1호
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• pp.33-35
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• 2005

Perpendicular magnetization curves and crystal textures of $[Pd(0.8 nm)/Co(0.8 nm)]_5/FeMn$ multilayers having an exchange-biased perpendicular magnetic anisotropy as a function of FeMn thickness and annealing temperature were measured. As FeMn thickness increases from 0 to 21 nm, the perpendicular exchange biasing field ($H_{ex}$) obtained the maximum value of 130 Oe at FeMn thickness 12 nm. As the annealing temperature increases to $240^{\circ}C$, the H_ex increased from 115 Oe to 190 Oe and the exchange-biased perpendicular magnetic anisotropy disappeared at $330^{\circ}C$.

• Journal of Magnetics
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• 제18권1호
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• pp.5-8
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• 2013

The perpendicular magnetic anisotropy of sputtered CoFeB thin films covered by MgO was investigated by vibrating sample magnetometry. Three different $Co_xFe_{80-x}B_{20}$ alloys were studied. Under out-of plane magnetic field, the saturation field was found to increase with increasing the Co content. The magnetization and interface anisotropy energy were obtained for all samples. Both showed a marked dependence on the MgO overlayer thickness. In addition, their variations were found to be non-monotonous as a function of the Co concentration.

• Journal of Magnetics
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• 제7권3호
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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 Magnetics
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• 제11권2호
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• pp.70-73
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• 2006

The magnetization angle and thickness dependence of magnetic anisotropy in the exchange-biased [Pd/Co]${\times}$5/FeMn multilayers with an out-of-plane anisotropy were investigated to determine the origin of perpendicular exchange biasing. As the Co thickness increased to 1.5 nm in the [Pd(0.8 nm)/Co(t)]${\times}$5/FeMn(120 nm) films, the hysteresis loops were converted from square loops at a thin Co (<0.4 nm) to complicated round ones at a thick Co. The irregularly asymmetric step (IAS) at the left top of the loop appeared in the loop of the 0.6-nm Co film due to an inhomogeneity in the exchange anisotropy. As the Pd thickness increased to 1.6 nm, the step disappeared, and the perpendicular magnetic anisotropy was maximized in the Co thickness between 0.6 and 0.9 nm. The conversion of the magnetization loop along the magnetization angle coincided with the equation $H_{(eff)}=H_o\;cos{\theta}$. The IAS of the 0.8-nm Pd film disappeared after thermal annealing up to $200^{\circ}C$ under an external magnetic field.

• 한국자기학회지
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• 제2권3호
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• pp.251-256
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• 1992

고주파 마그네트론 스퍼터링에 의해 Co /Pd 인공초격자를 형성하였다. 형성시킨 Co /Pd 인공초격자의 조성변조를 소각 X-선회절 분석으로 확인하였으며, XRD 분석 결과 두 원소의 격자상수 차이로 인해 Co 격자 팽창이 일어남을 알 수 있었다. Co 층 두께가 8${\AA}$ 이하가 되면 Co /Pd 인공초격자는 수직자기이방성을 띠었으며, 특히 Co가 단원자층인 경우에는 보자력이 2350 Oe이었고, 자기이력곡선의 각형도 우수하였다. Co /Pd 인공초격자가 수직자기이방성을 가지는 원인은 Pd에 의해 Co 격자가 팽창되는 현상과 관계가 있으며, Pd 두께가 증가할수록 수직자기이방성이 커지는 것을 확인하였다. Co /Pd 인공초격자의 수직자기이방성 에너지와 Co 두께의 관계로부터 계면이방성 에너지와 부피이방성 에너지를 계산하였으며 이는 각각 0.29 ergs/$cm^2$와 -$6.9{\times}10^6$ ergs/$cm^3$이었다.

• 한국자기학회지
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• 제14권4호
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• pp.127-130
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• 2004

본 연구는 (pd/Co)$_{N}$FeMn 구조의 다층박막을 dc 마그네트론 스퍼터링 시스템으로 증착하여 교환결합된 수직이방성에 대한 자기적 특성과 열적안정성을 조사하였다. 반강자성 FeMn 두께를 0-2lnm에서 변화시키면서 측정한 결과 Ta(1.9 nm)/(Pd(0.8nm)/Co(0.8nm)$_{5}$Mn(15nm)/Ta(1.9nm)에서 127 Oe교환바이어스세기(exchange biasing field: H$_{ex}$)를 얻었다. 그리고 이 구조에서 열적 안정성을 조사하기 위하여 온도 변화에 따른 H$_{ex}$변화를 확인한 결과, 24$0^{\circ}C$까지는 H$_{ex}$가 115 Oe에서 195 Oe까지 증가하였고, 그 이후 33$0^{\circ}C$에서 교환 결합된 수직자기이방성 곡선이 사라지는 것을 관찰하였다.

• Journal of Magnetics
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• 제10권2호
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• pp.44-47
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• 2005

The oscillatory interlayer exchange coupling (IEC) has been shown in pinned $[CoFe/Pt(t_{pt})/CoFe]/IrMn$ multi-layers with perpendicular anisotropy. The period of oscillation corresponds to about 2 monolayers of Pt. The oscillatory behavior of IEC depending on the nonmagnetic metallic Pt thickness is thought to be related the antiferromagnetic ordering induced by IrMn layer. Oscillatory IEC as function of insulating NiO thickness has been observed in $[Pt/CoFe]_4/NiO(t_{NiO})/[CoFe/Pt]_4$ multilayers. The effect of N (number of bilayer repeats) upon the magnetic property of [Pt/CoFe]N/IrMn is also studied.

• Journal of Magnetics
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• 제14권3호
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• pp.101-103
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• 2009

The spin transfer torque efficiency was determined experimentally by observing the current-driven domainwall depinning of Pt/CoFe/Pt nanowires with perpendicular magnetic anisotropy. The depinning time was exponentially proportional to the applied magnetic field, and was well explained by the Neel-Brown formula. The depinning time and threshold magnetic field were varied considerably by injecting current into the nanowire. The spin transfer torque efficiency was estimated to be $(7.2{\pm}0.9){\times}10^{-15}Tm^2$/A from the linear dependence of the threshold current density with respect to the applied magnetic field.