• Journal of the Korean Magnetics Society
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• v.2 no.2
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• pp.119-124
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• 1992

We have investigated the effects of sputtering Ar gas pressure on magnetic and magneto-optical properties in compositionally modulated Co/Pd superlattice thin films. The samples were prepared by dc magnetron sputtering from 2-in.-diam Co and Pd targets by alternately exposing the substrates to targets. Sputtering Ar gas pressure was varied from 2 to 30 mTorr. All samples had same bilayer thicknesses composed of 2-$\AA$-thick Co and 9-$\AA$-thick Pd sublayers. It was observed that the colum-nar structure was more distinctively developed with increasing Ar gas pressure. We observed that the intrinsic uniaxial anisotropy energy, magnetization and polar Kerr rotation were decreased with increasing Ar gas pressures. Large coercivity and perfect squareness were attained by the deposition at the high Ar gas pressure. We believe that the results are mainly ascribed the variation of micro-structure with sputtering Ar gas pressure.

• Journal of Magnetics
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• v.11 no.2
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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.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.716-719
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• 1995

Pd/(Pt/Co/Pt) modulated multilayer films have been deposited on various substrates with Pd/Pt buffer layers. Films grown at different temperatures have very distinct magnetic properties and surface microstructures. Atomic force(AFM) and scanning tunneling (STM) microscopies studies of these films reveal that films deposited at room temperature have small grain structures with an average grain size of about $140\;{\AA}$. However, much larger grains of about $1200\;{\AA}$ in size are observed in the films grown on buffer layers which were deposited at $500^{\circ}C$. These large grains are found to actually consist of smaller grains of about $170{\AA}$ in diameter. SQUID magnetic and Kerr hysteresis loop measurements indicate that multilayer films with large grains exhibit high magnetic coercivities of around 5 kOe. A subgrain growth model is proposed to understand the observed grain structures in the multilayers.

• Journal of the Korean Magnetics Society
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• v.3 no.1
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• pp.56-60
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• 1993

We have investigated the dependence of the magnetization, anisotropy, coercivity, and Kerr rotation on the Fe concentration in FeCo/Pd multilayer thin films, where the Fe concentration in the FeCo sublayer varied between 0 and 100% with maintaining the same sublayer thickness of $2.5\;{\AA}$ FeCo and $10.5\;{\AA}$A Pd. The maximum saturation magnetization was observed at the Fe concentration of about 48at.% in the FeCo sublayer. Perpendicular magnetic anisotropy and coercivity of the FeCo/Pd multilayer thin film decreased monotonically with increasing the Fe con-centration. The Kerr rotation angle also decreased with increasing the Fe concentration and the amount of vari-ation was remarkably changed with decreasing the light wavelength.

• Korean Journal of Metals and Materials
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• v.47 no.6
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• pp.372-377
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• 2009

We report on hysteresis behavior in the electrical resistance-hydrogen concentration of Pd thin films. The variation of the electrical resistance has been investigated during the process of absorption and desorption of hydrogen gas ($H_{2}$) as a function of thickness of Pd thin films. The hysteresis behavior in the electrical resistance with $H_{2}$ concentration was found for Pd thin films and consists of $\alpha$ phase, ${\alpha}+{\beta}$ phase, and $\beta$ phase regions. The sensitivity of Pd thin films with $H_{2}$ concentration was found to follow Sieverts' law in the $\alpha$ phase region. However, the sensitivity was observed to increase abruptly with $H_{2}$ concentration in the ${\alpha}+{\beta}$ phase co-exist region. This is because Pd-H interaction is stronger in the $\beta$ phase than in the $\alpha$ phase and needs a higher concentration gradient as a driving force to desorb. The formation of the $\beta$ phase also was observed to cause the structural change because of the lattice expansion during absorption. The hysteresis height and the trace of structural change were affected by the thickness of the Pd film. As the film becomes thinner, the hysteresis height becomes lower and the amount of delamination on the surface becomes smaller. For films thinner than 20 nm in thickness, the delamination was not found but electrical resistance hysteresis was still observed.

• Proceedings of the Korean Magnestics Society Conference
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• 2001.04a
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• pp.112-113
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• 2001

• Proceedings of the Korean Magnestics Society Conference
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• 2001.10a
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• pp.102-103
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• 2001

• Proceedings of the Korean Magnestics Society Conference
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• 1995.10a
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• pp.26-27
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• 1995

• Journal of Korean Vacuum Science & Technology
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• v.5 no.2
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• pp.33-37
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• 2001

We measured x-ray magnetic circular dichroism of Co films on Pd(111) surface with and without Pd capping layer at the Co L$_2$,$_3$ edges. Perpendicular magnetization and orbital-moment enhancement are induced by the capping layer. The increase of perpendicular magnetic anisotropy induced by capping layer is considered to result from the increase of surface anisotropy due to the hybridization at the surface.

• Journal of the Korean Magnetics Society
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• v.4 no.3
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• pp.256-262
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• 1994

$200{\AA}$ thick Co/Pd multilayered thin films were fabricated by sputtering. Two thicknesses of cobalt sublayer, $2{\AA}$ and $4{\AA}$ were chosen and the effects of sputtering pressure on the perpendicular magnetic anisotropy were investigated. It has been found that the optimum pressure for maximum perpendicular magnetic anisotropy(PMA) existed and the pressure for maximum PMA was lower for the multilayer with $2{\AA}$ cobalt layer than that with $4{\AA}$ cobalt thickness. As the sputtering gas presssure increased, domain wall motion with magnetization became difficult and the predominant mode of magnetization reversal changed from domain wall motion to magnetic moment rotation. It turned out that the perpendicular magnetic anisotropy was higher in case of $2{\AA}$ cobalt thickness than $4{\AA}$ cobait thickness.