• 한국자기학회지
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• 제2권2호
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• pp.119-124
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• 1992

조성변조 Co/Pd 초격자 박막 제조시 스퍼터링 Ar기압이 박막의 미세조직에 미치는 방향과 이로 인한 자기 및 자기광학적 특성에 미치는 영향을 조사하였다. 초격자 박막은 dc-magnetron 스퍼터링 방법으로 각 sublayer의 두께가 $2\;\AA-Co/9\;\AA-Pd$일때, 스퍼터링 Ar가스압력을 2에서 30 mTorr 까지 변화시키면서 제조하였다. Ar기압이 10 mTorr 이상에서 초 격자 박막은 주상구조(columnar structure)를 형성시키면서 성장됨이 관측되었다. Ar기압의 증가에 따라 포화자화값, 자기이방성에너지 및 Kerr 회전각등은 감소하고 보자력은 증가함을 보였다. 이러한 자기 및 자기광학적 특성의 변화는 Ar압력에 따른 초격자 박막의 미세구조 변화에 기인되는 현상으로 설명될 수 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.444-444
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• 2011

Recently, patterned magnetic films and elements attract a wide interest due to their technological potentials in ultrahigh-density magnetic recording and spintronic devices. Among those patterned magnetic structures, magnetic anti-dot patterning induces a strong shape anisotropy in the film, which can control the magnetic properties such as coercivity, permeability, magnetization reversal process, and magneto-resistance. While majority of the previous works have been concentrated on anti-dot arrays with a single magnetic layer, there has been little work on multilayered anti-dot arrays. In this work, we report on study of the magnetic properties of bilayered anti-dot system consisting of upper perforated Co layer of 40 nm and lower continuous Ni layer of 5 nm thick, fabricated by photolithography and wet-etching processes. The magnetic hysteresis (M-H) loops were measured with a superconducting-quantum-interference-device (SQUID) magnetometer (Quantum Design: MPMS). For comparison, investigations on continuous Co thin film and single-layer Co anti-dot arrays were also performed. The magnetic-domain configuration has been measured by using a magnetic force microscope (PSIA: XE-100) equipped with magnetic tips (Nanosensors). An external electromagnet was employed while obtaining the MFM images. The MFM images revealed well-defined periodic domain networks which arise owing to the anisotropies such as magnetic uniaxial anisotropy, configurational anisotropy, etc. The inclusion of holes in a uniform magnetic film and the insertion of a uniform thin Ni layer, drastically affected the coercivity as compared with single Co anti-dot array, without severely affecting the saturation magnetization ($M_s$). The observed changes in the magnetic properties are closely related to the patterning that hinders the domain-wall motion as well as to the magneto-anisotropic bilayer structure.

• Journal of Magnetics
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• 제14권1호
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• pp.18-22
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• 2009

The shape anisotropy effect of a giant magnetoresistance-spin valves (GMR-SV) device with a glass/NiO/NiFe/CoFe/Cu/CoFe/NiFe layered structure for use in the detection of magnetic property of molecules within a cell was investigated. The patterned device was given uniaxial anisotropy during the sputtering deposition and vacuum post-annealing, which was performed at $200^{\circ}C$ under a 300 Oe magnetic field. The pattern size of the device, which was prepared through the photolithography process, was $2{\times}15\;{\mu}m^2$. The experimental results confirmed that the best design for a GMR-SV device to be used as a biosensor is to have both the axis sensing current and the easy axis of the pinned NiO/NiFe/CoFe triple layer oriented in the direction of the device's width, while the easy axis of the free CoFe/NiFe bilayer should be pointed along the long axis of the device.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.251-251
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• 2012

A lot of studies are undergoing on the magneto-optical (MO) properties of patterned magnetic systems for the reason that they have potential application to information technology such as ultrahigh-speed computing. Moreover, they can be considered as the future candidates for high-density MO storage devices. Not only the technical aspects, but there have been also tremendous interests in studying their properties related to the fundamental physics. The MO Kerr-rotation effects (both in reflected and the diffracted modes) and the magnetic force microscopy (MFM) are very useful techniques to investigate the micromagnetic properties of such periodic structures. Hence, in this study, we report on the MO properties of bilayered Cobalt (Co)/ nickel (Ni) micro-patterned anti-dot arrays. Such a ferromagnetic structure was made by sequentially depositing co (40 nm)/Ni (5 nm) bilayer on a Si substrate. The anti-dot patterning with hole diameter of $1{\mu}m$ was done only on the upper Co layer using photolithography technique, while the Ni underlayer was kept uniform. The longitudinal Kerr rotation (LKR) of the zeroth- and the first-order diffracted beams were measured at an incidence of $30^{\circ}$ by using a photoelastic modulator method. The external magnetic field was applied perpendicularly to the reflected and the diffracted beams using an electromagnet capable of a maximum field of ${\pm}5$ kOe. Significantly, it was observed that the LKR of the first-order diffracted beam is nearly 4 times larger than that of the zeroth-order beam. The simulated results for the hysteresis loops matched qualitatively well with the experimentally obtained ones. In conjunction with the LKR, we also investigated the magnetic-domain structure by using a MFM system, which were analyzed to elucidate the origin of the enhanced MO rotation.

• 한국자기학회지
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• 제17권4호
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• pp.172-177
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• 2007

셀(cell) 단위의 생체분자의 자성특성 검출을 위한 거대자기저항-스핀밸브(giant magnetoresistance-spin valves; GMR-SV) 바이오센서로서 미세 패턴된 모양에 따라 길이 방향과 폭 방향 용이축에 의존하는 자기저항 특성을 연구하였다. 바이오센서(biosensor)로서 사용할 스핀밸브 다층구조는 glass/NiO/NiFe/CoFe/Cu/CoFe/NiFe 이었다. 자성 다층박막의 일축이방성을 만들기 위해 증착시와 소자 패턴닝 후 진공 열처리를 $200^{\circ}C$에서 300 Oe 정도 외부자기장을 인가하였다. 형상자기이방성 효과를 고려하여 광 리소그래피 과정으로 얻은 미세 활성영역 패턴 사이즈는 $2{\times}5{\mu}m^2$로 정하였다. 2단자법으로 길이방향의 센싱전류와 폭 방향의 고정층의 용이축 방향 각도에 의존하는 자장민감도의 변화는 바이오센서 소자로서 활용에 중요한 요인임을 확인하였다.

• 한국자기학회지
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• 제23권4호
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• pp.122-125
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• 2013

비정질 합금인 CoSiB과 비자성체 Pd을 이용하여 CoSiB/Pd 다층박막을 제작하고, 그 자기적인 특성을 분석하였다. $[CoSiB\;t_{CoSiB}/Pd\;1.3nm]_5$ 다층박막을 $t_{CoSiB}$ = 0.1~0.6 nm의 범위로 제작하였고, 동일한 방법으로 $[CoSiB\;0.3nm/Pd\;t_{Pd}]_5$ 다층박막을 $t_{Pd}$ = 1.0~1.6 nm의 범위로 제작하여 두께에 따른 자기이방성과 포화자화도를 측정하였다. CoSiB 두께가 증함에 따라 포화자화도가 증가하는 경향을 보였는데, 특히 CoSiB의 두께가 0.2~0.3 nm 일 때 포화자화도가 급격하게 증가하였다. 보자력은 두께 0.2 nm 에서 최대값을 보이다가 두께가 증가함에 따라 점차 감소하는 것을 확인하였다. Pd의 두께 변화 실험에서는 포화자화도는 1.1~1.2 nm 구간에서 약간 감소하다가 1.3 nm 이후 점차 증가하였으며, 보자력은 포화자화도에 비해 확연한 규칙성을 보이지 않았으나, 전체적으로 Pd의 두께가 증가함에 따라 값이 감소하는 것을 알 수 있었다.