• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.622-629
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• 2004

In this paper, effects of elastic energy of magnetostrictive film on the deflection of a cantilevered film-substrate system are investigated. The total energy including the elastic energy of magnetostrictive film is formulated. And it is minimized to give the curvatures and the position of neutral axis of the cantilevered system. To discuss the effects of the elastic energy of film in a measured system, three magnetostrictive unimorph cantilevers and a bimorph cantilever reported elsewhere are reviewed. It is shown that the assumption, since the thickness of film is much smaller than that of substrate the film elastic energy is negligible, can cause considerable error in evaluating magnetostrictive coefficients. Not the ratio of thicknesses but elastic energies between film and substrate is also shown to play important role in making decision whether the assumption is valid or not.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권5호
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• pp.289-293
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• 2000

This paper presents a study on the linear compensation of nonlinear hysteric actuators using the highly magnetostrictive film pattern as a strain sensor. Elements had a hybrid structure, in which thin soft glass substrate with the highly magnetostrictive amorphous FeCoSiB film was bonded on the PZT piezoelectric substrate. The magnetostrictive film as a strain sensor detects the deflection of an actuator, and a voltage signal from the strain sensor related to the deflection of an actuator is used for the linear control of an actuator.

• Journal of Magnetics
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• 제2권3호
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• pp.76-85
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• 1997

Magnetic and magnetostrictive properties of Tb-Fe and Tb-Fe-B thin films are systematically investigated over a wide composition range from 40.2 to 68.1 at. % Tb. The films were fabricated by rf magnetron sputtering using a composite target which consists of an Fe plate and Tb chips. The microstructure, examined by X-ray diffraction, mainly consists of an amorphous phase and, at high Tb contents, a pure Tb phase also exists. A progressive change in the direction of anisotropy from the perpendicular to in-plane occurs as the Tb content increases and the boundary at which the anisotropy change occurs shifts significantly towards to higher Tb contents with the addition of B. The saturation magnetization exhibits maxima at the Tb contents of 42 and 48 at. % for Tb-Fe and Tb-Fe-B thin films, respectively, and it is decreased by the addition of B. The coercive force, measured in the easy direction, decreases monotonically with the Tb content. Excellent magnetostrictive characteristics, particularly at low magnetic fields, are achieved in both Tb-Fe and Tb-Fe-B thin films; for example, a magnetostriction of 138 ppm is obtained in a Tb-Fe-B thin film at a magnetic field as low as 30 Oe. The excellent magnetostrictive properties of the present thin films are supported by the equally excellent magnetic softness, the coercivity below 10 Oe and a typical squared-loop shape with the saturation field as low as 1 kOe. Due to the excellent low field magnetostrictive characteristics, the present Tb-Fe based thin films are thought to be suitable for Si based microdevices.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1617-1620
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• 2007

This paper presents a magnetostrictive transpositioner and its fabrication process. To get a transposition movement without shifting or twisting, it is designed as an array type. To fabricate the suggested design, micromachining and selective DC magnetron sputtering processes are combined. TbDyFe film is sputter-deposited on the back side of the bulk micromachined transpositioner, with the condition as: Ar gas pressure below $1.2{\times}10^{-9}$ torr, DC input power of 180W and heating temperature of up to $250^{\circ}C$ for the wireless control of each array component. After the sputter process, magnetization and magnetostriction of each sample are measured. X-ray diffraction studies are also carried out to determine the film structure and thickness of the sputtered film. For the operation, each component of the actuator has same length and out-of-plane motion. Each component is actuated by externally applied magnetic fields up to 0.5T and motion of the device made upward movement. As a result, deflections of the device due to the movement for the external magnetic fields are observed.

• Journal of Magnetics
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• 제3권2호
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• pp.55-63
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• 1998

Magnetic and magnetostrictive properties of amorphous Sm-Fe and Sm-Fe-B thin films are systematically investigated over a wide composition range from 14.1 to 71.7 at.% Sm. The films were fabricated by rf magnetron sputtering using a composite target composed of an Fe (or Fe-B) plate and Sm chips. The amount of B added ranges from 0.3 to 0.8 at. %. The microstructure, examined by X-ray diffraction, mainly consists of an amorphous phase in the intermediate Sm content range from 20 to 45 at.%. Together with an amorphous phase, crystalline phases of Fe and Sm also exist at low and high ends of the Sm content, respectively. Well-developed in-plane anisotropy is formed over the whole compositionrange, except for the low Sm content below 15 at.% and the high Sm content above 55 at %. As the Sm content increases, the saturation magnetization decreases linearly and the coercive force tends to increase, with the exception of the low Sm content where very large magnitudes of the saturation magnetization and the coercive force are observed due to the existence of the crystalline $\alpha$-Fe phase. The coercive force is affected rather substantially by the B addition, resulting in lower values of the coercive force in the practically important Sm content range of 30 to 40 at.%. Good magnetic softness indicated by well-developed in-plane anisotropy, a square-shaped hysteresis loop and a low magnitude of the coercive force results in good magnetostrictive characteristics in both Sm-Fe-B thin films. The magnetostrictive characteristics, particularly at low magnetic fields, are further improved by the addition of B; for example, at a magnetic field of 100 Oe, the magnitude of magnetostriction is -350 ppm in a Sm-Fe thin film and it is -470 ppm in a B containing Sm-Fe thin film.

• 한국자기학회지
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• 제13권5호
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• pp.193-197
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• 2003

우수한 연자성 특성과 자왜 특성을 동시에 나타내는 철계 아몰퍼스 박막을 이용한 고기능성 센서나 신호처리소자와 같은 자기탄성 디바이스를 구현하기 위해서는 자기이방성의 제어가 필요하다. 본 연구에서는 철계 아몰퍼스 박막의 자기이방성을 제어하기 위해서 바이어스 응력을 이용한 자기이방성제어 방법을 제안하였다. 제안한 방법은 박막의 기판을 굴곡시킨 상태에서 열처리를 실시하여 박막의 응력을 해소하고, 열처리 후 박막기판의 형상을 원상으로 복귀시켜서 박막에 바이어스 응력이 인가되도록 하고, 이 응력에 의해서 박막의 자기이방성이 제어되도록 하는 것이다. 응력을 이용하여 자기이방성을 제어한 박막패턴을 자구의 관찰과 자화곡선의 평가를 고찰한 결과, 제안한 자기이방성 제어방법이 유용함을 알 수 있었다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 1999년도 춘계연구발표회 논문개요집
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• pp.40-41
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• 1999

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3328-3330
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• 1999

In this paper, the fabrication of a micro actuator with a micro electromagnet and an actuator diaphragm is presented. The micro electromagnet consists of a magnetic core and a micro inductive planar coil. The actuator diaphragm is the p+ silicon diaphragm on both sides of which magnetostrictive materials are deposited by sputtering. The micro electromagnet is fabricated by sputtering, evaporating, etching and electroplating. The magnetic flux density of the micro electromagnet is measured by using the gauss meter. The deflection of the actuator diaphragm is measured by using the laser vibrometer and optic microscope.

• 한국자기학회지
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• 제13권4호
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• pp.133-154
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• 2003

A comprehensive review is given in this article on magnetic and magnetostrictive properties of nanogranular Co-Fe based alloys, with a particular emphasis on high frequency applications. Structural and physical properties are firstly described, followed by magnetic and magnetostrictive properties. Materials of both thin film and bulk forms are considered. A detailed description on high frequency characteristics of Co-Fe based soft magnetic thin films is then presented.

• 한국자기학회지
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• 제10권5호
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• pp.237-245
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• 2000

SmFe$_2$에 해당되는 조성을 가진 비정질 합금 박막에 대하여 자기적 및 자기변형 성질이 B함량 (최대 약 10at.%) 및 열처리에 의해 변화하는 거동을 조사하였다. 묘의 첨가에 의해 낮은 자기장에서의 자기변형은 증가하였으나, 포화 자기 변형은 감소하는 경향을 보였다. B을 첨가하지 않은 박막과 B을 9.9 at.% 첨가한 박막을 예로 들면, 30 Oe의 자기장에서 자기변형은 190 ppm에서 333 ppm으로 1.6배 정도 증가하였으나, 5 kOe의 자기변형은 50 % 이상 감소되었다. 이러한 자기변형 결과는 B의 첨가에 의해 포화 자화와 같은 고유 자기적 성질은 열화되었으나, 보자력은 향상(감소)된 것에 주로 기인하는 것으로 생각된다. 자기변형 성질은 열처리에 의해 향상되었는데, 최적의 열처리 온도는 300~40$0^{\circ}C$이다. 열처리에 의한 이러한 특성 향상은 당초 기대했던 미세한 결정 상 SmFe$_2$상의 석출에 의한 것이 아니라, 응력 완화에 의한 보자력의 감소가 주된 원인으로 생각된다.