• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.180-181
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• 2002

수직기록매체에서 기록 밀도가 증가하기 위해서는 bit의 크기를 줄여야 하고, 이를 위해서는 writing head의 width와 thickness를 줄여야 한다. 그러나 head의 크기가 줄어들면 기록층의 자화를 반전시키기에 충분한 write field를 얻지 못한다. 이를 극복하기 위해 head의 tip부분을 trimming을 하여 작은 pole tip 크기를 가지면서도 큰 write field를 얻고, 여분의 magnetic field를 얻기 위해 soft underlayer를 도입하는 이중층 수직기록 매체가 제안되고 있다. (중략)

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.8
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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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.883-887
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• 2006

In order to attain high-rate deposition of Mn-Zn ferrite thin film for soft magnetic underlayer in perpendicular magnetic recording media, a reactive sputtering using powder-metal targets under the mixture gas of Ar and $O_{2}$ was performed. It was succeeded that Mn-Zn ferrite films with (111) crystal orientation were deposited on Pt(111) underlayer without any annealing process. The film revealed 3.4 kG of 4 ${\pi}Ms$, 70 Oe of coercivity. The deposition rate of the new method was 16 times as high as that of the conventional method using ferrite target.

• Journal of Magnetics
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• v.11 no.2
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• pp.83-86
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• 2006

Controlling magnetic domains in soft underlayer (SUL) of perpendicular magnetic recording (PMR) is an important issue for the application of PMR in HDD. We studied the magnetic domain structures in SUL using the finite element based micromagnetic simulation (FEMM) for the SUL models with different thicknesses. The purpose is to simulate the magnetic domain wall noise when the SUL thickness and saturation magnetization are changed. The simulation results show that a 15 nm SUL forms simpler Neel wall domain wall pattern and 40 nm SUL forms complex Bloch wall. To visualize the effect of these domain walls stray field at a read sensor position, the magnetic stray field of the domain walls at air bearing surface (ABS) which is 50 nm above the SUL was simulated and the results imply that Bloch walls have stronger stray field with more complicated field patterns than Neel walls and this becomes a significant noise source. Therefore, the thickness of the SUL should be controlled to avoid the formation of Bloch walls.

• Proceedings of the Korean Magnestics Society Conference
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• 2005.06a
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• pp.28-29
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• 2005

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.230-231
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• 2003

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11C
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• pp.896-900
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• 2010

We investigate the bit error rate against signal-to-noise ratio performance corresponding to track mis-registration for patterned media storage. The patterned media channels with and without soft underlayer are implemented, and we simulate using one-dimensional Viterbi detector and two-dimensional soft output Viterbi detector (SOVA) when the track mis-registration is 0% (on-track), 10%, 20%, 30%, and 40%. While the BER performance degrades approximate 0.3 ~ 0.5 dB at 10% track mis-registration, it degrades severe over 10% track mis-registration.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.112.2-112.2
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• 2007

• Proceedings of the Korean Magnestics Society Conference
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• 2000.05a
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• pp.132-133
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• 2000

• Proceedings of the Korean Magnestics Society Conference
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• 2005.06a
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• pp.30-31
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• 2005