• Journal of Magnetics
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• 제16권4호
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• pp.403-407
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• 2011

Metal-insulator type, nano-granular soft magnetic films have been reviewed from the viewpoint of high frequency magnetic materials. The formation of nano-granular structure is related to the magnitude of heat of formation of intergranule materials. Variation of the ratio of granule phase to intergranule phase in the film is found to produce various characteristics in the magnetic properties of the film. The HRTEM observation reveals that neighboring granules in the film with above 60 at.% Co, contact at considerable points and the films show soft magnetic properties which are explainable in terms of the random anisotropy model for nano-crystalline materials. Addition of Ni group elements in Co-O based films enhances their anisotropy field up to 400 Oe and they exhibit excellent frequency response of permeability. Also, large electromagnetic noise suppression effect is demonstrated as one of their potential applications.

• 마이크로전자및패키징학회지
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• 제11권3호
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• pp.31-36
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• 2004

연자성 차폐필름에 대하여 ASTM 방법 및 2-port flanged coaxial line 방법으로 RF (radio-frequency) 영역에서 전자기파 차폐특성을 측정하여 원역장에서의 차폐요인을 정량적으로 분석하였다. 4-13.5 GHz의 고주파 영역에서 연자성 차폐필름의 차폐효과는 반사손실에 의한 효과가 아니라 주로 흡수손실에 의한 차폐효과를 가졌다.

• 한국자기학회지
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• 제14권2호
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• pp.59-64
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• 2004

나노 결정립 구조를 갖는 Fe-Al-O 연자성 산화막을 이온빔 에칭법으로 에칭하면서 연자기적 특성의 변화를 조사하였다. 두께가 감소할수록 보자력과 각형비가 증가하고 AFM 으로 조사한 표면굴곡도 증가하는 것으로 보아 결정립의 크기가 증가하는 것으로 판단된다. 이러한 현상은 비정질을 열처리한 나노결정립 연자성 재료와 다르게 성막하는 과정의 온도 상승에 의한 결정성장이 원인으로 판단된다. 따라서 우수한 연자성 박막을 제조하기 위해서는 두께 및 성막시간 등 최적 제조조건을 찾아야 한다. 마그네트론 스퍼터링법으로 제조된 Fe-Al-O 산화막의 경우 900 nm 이상에서 보자력이 1 Oe 이하인 연자성 박막을 얻을 수 있었다.

• Current Applied Physics
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• 제18권11호
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• pp.1196-1200
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• 2018

We have experimentally demonstrated circular polarization generation from linear polarized soft X-ray at synchrotron by adopting a thin magnetic film polarizer. Polarizer is composed of Co/Pt multilayer with a perpendicular magnetic anisotropy, which allows us to easily accommodate without needing any tilting angle into the measurement setup since the circular polarization is generated for the X-ray with normal incidence and transmission. Generated circular polarization is examined by observing magnetic domain features based on the X-ray magnetic circular dichroism, where~11% of circular component is estimated compared to the case of full circular polarization.

• 한국자기학회지
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• 제19권4호
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• pp.142-146
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• 2009

이온빔 증착법으로 제작한 코닝유리(Corning glass)/Ta(5 nm)/(Permalloy, Conetic)/Ta(5 nm) 박막에 대한 연자성의 특성에 대해 연구하였다. 퍼멀로이(Permalloy; NiFe)층과 코네틱(Conetic; NiFeCuMo)층을 증착하여 인가 자기장 방향에 용이축과 곤란축의 자기저항곡선으로부터 얻은 보자력과 포화자기장에 대해 각각 비교하였다. 두께가 10${\sim}$15 nm인 코네틱 박막의 표면저항값은 퍼멀로이 박막보다 2배 정도 높았으나 보자력과 포화자기장은 1/3배 정도 낮았으며, 자화율은 2${\sim}$3배 정도 높은 초연자성의 특성을 가졌다. 퍼멀로이 박막보다 연자성의 특성이 높은 코네틱 박막을 이용한 스핀밸브나 터널접합의 소자를 개발할 수 있는 가능성을 확인하였다.

• Journal of Magnetics
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• 제10권4호
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• pp.163-170
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• 2005

The RF integrated noise filters are fabricated by photolithography. The stack for the electromagnetic noise filters consists of the nano-granular ($Co_{41}Fe_{38}AI_{13}O_8$) soft magnetic film / $SiO_2$ / Cu transmission line / seed layer (Cu/Ti) / $SiO_2$-substrate. A good signal-attenuation feature along with a low signal-reflection feature is observed in the present filters. Especially in the noise filter incorporated with a $Co_{41}Fe_{38}AI_{13}O_8$ magnetic film with lateral dimensions of $2000{\mu}m$ wide, 15 mm long and $1{\mu}m$ thick, the maximum magnitude of signal attenuation reaches -55 dB, and the magnitude of signal reflection is below -10 dB in the overall frequency range. And this level of signal attenuation is much larger than that of a noise filter incorporated with a Fe magnetic film.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.478-480
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• 2001

Fe-base amorphous films exhibit large saturation magnetostriction and soft magnetic Properties, which make them suitable for strain sensor applications. Most important material properties for the performance of these elements are the superior soft magnetic properties, such as high permeability and small coercive force, as well as magnetoelastic properties. It is well known that the strain generated in film deposition and/or post-heat treatment processes is one of important material properties, which effects on the soft magnetic properties of the film via magnetoelastic coupling. In this study, the effect of an isotropic strain in plane of magnetic films have been performed experimently. Amorphous films with the composition of (F $e_{90}$ $Co_{10}$)$_{78}$S $i_{l2}$ $B_{10}$ were employed in this study. The film with 5${\mu}{\textrm}{m}$ thick was deposed onto the polyimide substrate with 50${\mu}{\textrm}{m}$ thick by virtue of RF sputtering. The film was subject to post annealing with a static magnetic field with 500Oe magnetic field intensity at 35$0^{\circ}C$ for 1 hour. The polyimide substrate with the film was bonded with an adhesive on PZT piezoelectric substrate with 600${\mu}{\textrm}{m}$ thick in applying voltage of 500V. The change in MH loops of films due to the isotropic strain was measured by using VSM. The coercive force was evaluated from MH loops. It has shown in the results that M-H loops of films are subject to change considerably with a dc voltage, resulting of the magnetization rotation from normal to plane direction as the applied voltage is changed from 500V to 250V.50V.V.

• 한국재료학회지
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• 제14권11호
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• pp.780-785
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• 2004

The degradation mechanism of soft magnetic properties of $Fe-Hf-N/Cr/SiO_2$ thin films reacted with a bonding glass was investigated. When $Fe-Hf-N/Cr/SiO_2$ films were annealed under $600^{\circ}C$ without the bonding glass, the compositions and the soft magnetic properties of Fe-Hf-N layers were not changed. However, after reaction with the bonding glass at $550^{\circ}C$, the soft magnetic properties of the film were degraded. At $600^{\circ}C$, the saturation magnetization of the reacted film decreased to 13.5 kG, and its coercivity increased to 4 Oe, and its effective permeability decreased to 700. It was founded that O diffused from the glass into the Fe-Hf-N layers during the reaction and generated $HfO_2$ phases. It was considered that the soft magnetic properties of the $Fe-Hf-N/Cr/SiO_2$ films reacted with the bonding glass were primarily degraded by the formation of the Fe-Hf-O-N layer of which the Fe content was below 60 $at\%$, and secondarily degraded by the Fe-Hf-O-N layer above 70 $at\%$.

• 한국자기학회지
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• 제7권5호
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• pp.243-248
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• 1997

Ar+ $O_{2}$ 혼합가스 중에서 반응성 스퍼터링을 통해 직접 Fe-Hf-O계 초미세결정 연자성 박막을 제조하였으며, 이때 산소분압비의 변화가 Fe-Hf-O 박막의 미세구조 및 자기적 특성에 미치는 영향을 조사하였다. 산소분압이 증가함에 따라 박막의 포화자속밀도는 점차적으로 감소하며 연자기특성이 10%까지는 향상되다가 다시 열화되는 경향을 나타내었다. 최적조건인 10%의 산소분압에서 증착한 F $e_{82}$H $f_{3.4}$ $O_{14.6}$ 초미세결정 박막은 열처리 없이 증착한 상태에서 우수한 연자기 특성을 나타내었으며, 이때의 자기적 특성은 각각 포화자속밀도 17.7 kG, 보자력 0.7 Oe 및 실효투자율 2,500(100 MHz)의 값을 나타내었다. 산소분압이 증가함에 따라 결정립 크기가 감소하며 15% 이상의 산소분압에서는 F $e_{3}$ $O_{4}$가 생성되었다. 따라서 10%에서 가장 우수한 연자기 특성을 나타내는 것은 결정립 크기와 산화물 생성에 의해 설명될 수 있다. Fe-Hf-O계 초미세결정 박막의 전기비저항은 산소분압이 증가함에 따라 증가하는 경향을 나타내었다. 우수한 연자기 특성을 나타내는 F $e_{82}$H $f_{3.4}$ $O_{14.6}$ 박막의 경우, 약 150 .mu. .ohm.cm로 산소를 첨가하지 않은 경우의 30 .mu. .ohm. cm에 비하여 약 5배 증가된 값을 나타내었다. 따라서 F $e_{82}$H $f_{3.4}$ $O_{14.6}$초미세결정 박막이 고주파에서 우수한 연자기 특성을 나타내는 원인은 주로 높은 전기비저항과 미세하게 형성된 결정립에 기이한 것으로 생각된다.

• Applied Microscopy
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• 제48권4호
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• pp.128-129
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• 2018

Soft ferromagnetic materials are utilized for various electromagnetic devices such as magnetic recording heads and magnetic shielding. In situ observation of magnetic microstructures and domain wall motions are prerequisite for understanding and improving their magnetic properties. In this work, by the Fresnel (out-of-focus) method of Lorentz microscopy, we observe the domain wall motions of polycrystalline Ni/Ti thin film layers triggered by single-shot laser pulse. Random motions of domain walls were visualized at every single pulse.