펄스전자석에 의한 자기이력곡선측정기

이장로,이용호,신용돌,이영희 숙명여자대학교 자연과학연구소 1993 자연과학논문집 Vol.- No.4

보자력이 큰 강자성체의 자기이력곡선, 자기변형, 자기이방성등의 측정에 사용할 수 있는 펄스전자석을 설계제작하였다. 철심의 형상이 주어졌을 때 권선의 회수에 따른 전자석의 여러특성과 축전기 방전시의 전류진폭 감쇄비등을 계산하는 일반식을 유도하고 그것에 의하여 철심단면적 46mm×32mm, 공기간격 28mm의 전자석을 설계 제작하여 20mT/A의 기울기로 0.49T까지 직선적인 자기장대 전류특성을 얻었다. 이 전자석에 애너로그 적분기에 의한 자속계를 부쳐서 박막 또는 박대시료의 major 및 minor 이력곡선을 단번에 쉽게 얻을 수 있는 자기이력곡선 측정기가 구성되었다. A pulsed electromagnet with silicon steel core driven by alternating current or oscillatory decaying current using capacitor discharging method for measuring magnetic hysteresis loops, magnetostriction and magnetic anisotropy of high coercivity magnetic sample is built. The general formuli for various characteristics of the electromagnet with given geometry of iron core and turns of copper wire are presented. Using these formuli, an electromagnet with 46mm×32mm of core's cross section and 28mm of air-gap is designed and built, its magnetic field to current ratio of 20mT/A is linear up to 0.49T. Combining this electromagnet with an analog integrated fluxmeter, a magnetic hysteresis loop can be easily displayed major and minor loops of thin film or strip at once.

Permally 박막의 Kerr 자광효과 특성

李章魯 淑明女子大學校 1980 論文集 Vol.20 No.-

The Kerr magneto-optic propeties of the thin film of Ni(80%) Fe(20%) alloy have been investigated. The homogenoneous permalloy films were obtained by annealing the double-layered films, prepared by evaporating a Ni film first on microscope glass and then a Fe film on it. To get the good ferromagnetic properties, Ni-Fe double-layered films must be annealed for more than ten hours at temperature 400℃ in vacuum of 10^-5∼10^-6 Torr. The magnetic hysteresis loop of permalloy film of the thickness 1000A˚measured by magneto optical method are rectangular, that is, the remanent magnetization equals the saturation magnetization. The Kerr magneto-optic effect of the film is investigated by measuring the rotation angle of the polarization and the ellipticity of the reflected light from the film surface using an ellipsometer. The rotation angles are so small that a Faraday cell is employed to improve the experimental accuracy. The state of polarization is analytically represented by using the poincare'-sphere. The optical indices such as the refractive index, the index of absorption, the magneto-optic amplitude, its phase are obtained by analyzing the measured rotation angles and ellipticities in terms of the reflection coefficient derived by Voigt. The absorption coefficient, the figure of merit, the electric conductivity, and the electric polarizability are also calculated using the above quantities. The dependence of the magneoto-optic constants upon the wave length of the light have also been investigated. The largest values of Kerr rotation, Magneto-optic amplitude and figure of merit obtained near the wavelength 6,100A˚are attributed to the resonance of the electric conductivity term and polarizability term of off-diagonal elements of the dielectric tensor. It is found that the center of the dispersion of magneto-optic constants is at the above region of the wavelength showing that the magneto-optic transition occurs around this wave length.

공진법에 의한 박막 및 기판의 영율 측정

이장로,이용호,신용돌 숙명여자대학교 자연과학연구소 1993 자연과학논문집 Vol.- No.4

유리기판 및 그 위에 증착된 박막의 각각의 영율을 외팔보의 기계적 공진주파수를 측정하여 계산하였다. 이 방법으로 얻어진 Ni와 ?? 박막에 대한 값은 bulk 상태의 기존치와 5%의 범위에서 일치하였다. 박막을 입힌 기판의 Q 값은 기판 자체의 Q 값보다 감소한 것으로 보아 박막을 입힌 기판의 내부마찰이 커짐을 알 수 있다. Young's Moduli of a substrate and thin films evaporated on its surface are calculated from the mechanical resonance frequency of cantilevered sample. The values for Ni and ?? films obtained by this method agree with published data for the bulk material within 5%. Internal friction of the substrate coated with film samples turns out to be larger than that of the substrate itself since the Q value becomes small when the films are coated.

非晶質合金 Fe-B 系의 磁氣 및 Kerr 效果特性

李章魯 淑明女子大學校 1992 論文集 Vol.32 No.-

급냉법 중 single-roll법을 이용하여 조성비가 다르게 제작한 ribbon형 Fe_(1-x)B_x(B=14%, 17%, 20%, 23%, 25%)와 진공도 1∼3×10^-6 Torr로 유지하면서 같은 조성의 Fe_(1-x)B_x계 ribbon을 유리기판에 진공증착하여 제작한 박막의 B함량에 따른 자기 및 자기광학적 특성을 연구하였다. X-선 회정장치로 ribbon형 Fe-B가 비정질임을 확인하였고, 조성비가 다른 ribbon시료에 대하여 Ar분위기에서의 소둔온도(100℃~400℃)를 달리하면서 B조성에 따른 포화자화도, 항자력을 시료진동형 자기계로 조사하였다. B함량이 증가함에 따라 Fe원자당 자기 모멘트는 감소하고 열처리 온도에 따른 항자력의 변화는 거의 없었다. 제작한 박막에 관한 자기광 특성은 타원편광해석장치로 측정하였고 B함량의 증가에 걸쳐 longi-tudinal Kerr회전각이 polar Kerr회전각보다 크게 나타났다 The magnetic and magneto-optic properties of the Fe_(1-x)B_x ribbon style and thin film were studied in particular attention paied to the amount of B(B=14%, 17%, 20%, 23%, and 25%). Fe_(1-x) B_x ribbon style samples were prepared using single roller quenching method. Fe_(1-x)B_x films were coated on the glass under the vacuum condition(1∼3×10^-6 Torr). X-ray diffraction of the sample was estimated by annealing the sample at different temperature between 100℃ and 400℃ under Ar atmosphere. The magnetization and coercive force of the samples were studied using VSM. The magnetic moment of Fe per transition atom decreased with increasing the amount of B in the sample. The coercive force remained constant independent of annealing temperture. The magneto-optic rotation angle of the thin film was bigger in the longitudinal-Kerr rotation angle than that in the polar-Kerr rotation angle.

Ribbon형 Co1-x Crx (x=0.27, 0.29, 0.30, 0.32, 0.35) 합금의 자기특성

장현숙,김미양,이장로,이용호 숙명여자대학교 자연과학연구소 1994 자연과학논문집 Vol.- No.5

급냉법으로 리본형 결정질 Co1-x Crx (x=0.27, 0.29, 0.30, 0.32, 0.35)합금을 제조하여 Cr의 조성에 따른 자기적 특성을 조사하였다. 포화자화값은 벌크값보다 컸지만 박막의 경우보다는 작았다. Cr의 함량이 증가함에 따라 포화자화값은 감소하였다. 27 at.% Cr의 경우를 예외로 하면 Cr 함량 증가에 따라 결정립의 크기는 감소하였고, 항자력은 증가하였다. 리본형 Co1-x Crx 는 포화자화값의 온도 의존성이 비정질 시료인 경우와 유사한 경향을 나타내었으며 Cr의 함량이 증가할수록 Curie온도(Tr)는 감소하였다. Cr 함량의 증가에 따라 exchange interaction의 평균자승거리<r²>와 spin wave stiffness 상수D는 감소하는 경향을 나타내었다. 천이금속(Co)의 원자당평균 자기모멘트는 Cr의 증가에 따라 선형적으로 감소하였다. The magnetic cnaracteristics of crystalline Co1-x Crx (x=0.27, 0.29, 0.30, 0.32, 0.35) ribbons prepared by the rapid solidification were investigated. The saturation magnetization for ribbon was greater than that for bulk alloys containg the same amount of Cr. but smaller for the films. The grain size of ribbon became smaller and coercive force increased with increasing Cr contents except case of 27 at.% Cr. The saturation magnetization decreased with increasing Cr contensts. The temperature dependence of saturation magnetization for Co1-x Crx ribbon showed the similar behavior as the amorphous alloy and the Curie temperatures were decreased with the increase of Cr contents. The spin wave stiffness constant and the mean square range of exchange interaction, also were decreased. The average magnetic moment per transition metal atom was linearly decreased with increasing the contents of Cr.

非晶質 Ge薄膜의 光學常數와 吸收端에 관한 硏究

李章魯 淑明女子大學校 1982 論文集 Vol.22 No.-

The optical properties of amorphous Ge films are studied in the 0.3∼2.0㎛(4.14∼0.62eV) spectral range. The films are prepared by vacuum evaporation at room temperature in vacuum of 2∼3.5×10^-6 Torr. The optical constants are obtained from the analysis of simultaneous transmission data of two samples prepared exactly the same way but having slightly different thicknesses. The analysis is carried out in self-consistent way by iteration. Two pairs of samples 150Å, 270Å thick and 450Å, 600Å thick show that the latter have values roughly 0.1 lower in the refractive index and 0.05eV higher in the band gap energy than those of the former. Such results show that that latter is more dense packing than the former. As for the shapes of the absorption edge, both cases are found to be fairly sharp, the shapes of which shift higher energy by the thermal treatment.

펄스 강자장 발생 연구

이장로,이용호,신용돌,이영희 숙명여자대학교 자연과학연구소 1993 자연과학논문집 Vol.- No.4

고전압 대용량의 전해축전기에 축적된 전하를 다층 솔레노이드에 순간적으로 방전할 때 흐르는 대전류에 의하여 솔레노이드 내부에 순간적인 강자기장을 발생시켰다. 코일의 형상, 회수 및 축전기의 전기용량과 충전전압에 따르는 방전전류, 발생자장, 발생열량 등을 계산하였다. 제작된 장치는 300 V로 충전된 0.01 F의 축전기의 전하를 내경 14 mm, 길이 40 mm, 회수 217회의 솔레노이드에 방전하여 최대전류 750 A, 최대자장 4.52T, 반주기 8 ms의 결과를 얻었다. Pulsed high magnetic fields were generated by discharging a large capacitance charged with high voltage into air solenoid. The relations between intensity of discharged current, generated magnetic field intensity, thermal dissipation, capacitance, charged voltage and geometry of solenoid were obtained with computer simmulation. A small scale apparatus was built to get the data for regular scale device. The maximum field of 4.52T, maximum current of 750A and 8ms half period was obtained by discharging a 300V, 0.01F capacitance into a solenoid 14mm inner diameter, 40mm long and 217 turns.

Mn-X-As 박막의 자기 및 자기광학적 특성

李章魯,朴愛珠 淑明女子大學校 1984 論文集 Vol.25 No.-

For the Mn_5Ni_2As_4 and Mn_3Cu_4As_4, compound thin films magnetic and magneto-optic properties are studied. The films are prepared by vacuum evaporation. As, Ni, Cu and Mn films are evaporated successively onto glass substrates at room teperature. The experimental conditions of the evaporating process and thermal treatment of thin films of the Mn-X-As tennary system are examined. The specific conditions required are obtained to be more than ten hours of annealing at 300℃ in vacuum of 1∼5×10Torr. The formation of the compound films was confirmed by X-ray diffraction. The magnetic hysteresis loop of the films of the thickness 1000Å are measured by a magneto-optical method. The magneto-optic Kerr effect of the films are investigated by measuring the rotation angle of the polarization and the ellipticity of the reflected light from the film surface using an ellipsometer. The state of polarization is analytically represented by using the poincare' sphere. The optical indices such as the refractive index, the index of absorption, the magneto-optic amplitude, its phase are obtained by analyzing the measured rotation angles and ellipticities in terms of the reflection coefficient derived ay Voigt. The absorption coefficient, the figure of merit, the electric conductivity, and the electic polarizability are also calculated using the above quantities. The dependence of the magneto-optic constants upon the wave length of the light have also been investigated. The largest value of kerr rotation, magneto-optic amplitude and figure of merit obtained near the wave length 5400Å are attributed to the resonance of the electric conductivity term and polarizability term of off-diagonal elements of the dielectric tensor. It is found that the center of the dispersion of magneto-optic constants is at the above region of the wave length showing that the magneto-optic transition occurs around this wave length. The figures of merit of the films are smaller than those of MnBi. The Mn_5Ni_2As_4 and Mn_3Cu_4As_4 films are very resistant to oxidation by the surrounding atmosphere. The films seem promising as a magneto-optic memory medium.

MnSb_(1-χ)Te_χ 자기화합물 박막의 자기 및 자기광학적 특성

李章魯 淑明女子大學校 1986 論文集 Vol.27 No.-

The magnetic and magneto-optic properties of the MnSb_(1-x)Te_x magnetic cmpound films with thickness 2500∼3000Å are investigated MnSb_(1-x)Te_x films (o≤x≤0.9)are prepared by vacuum evaporation. Then Sb, Te, Mn films are evaporated successively onto glass substrates at room temperature. After being covered with SiO layer, these 3 layered films are annealed for 10 hours at temperature 573K in vacuum of 10^­5∼10^­6 Torr. Magnetic and mageneto-optic properties of these compounds are investigated by means of VSM(Vibrating Sample Magnetometer)and ellipsometery. It has been found that as compound ratio χ in MnSb_(1-x)Te_x films increases both the magnetization and Kerr rotation angle of films decreases, but the Curie temperature and crystal lattice constants of films are unchanged.

버퍼층 및 열처리 효과가 CoFe/Cu 다층박막의 자기저항에 미치는 영향

오미영,송은영,이장로,김희중,김경민,김미양 숙명여자대학교 자연과학연구소 1996 자연과학논문집 Vol.- No.7

DC magnetron sputtering방법에 의해 Corning glass기판 위에 ?? 형태로 다층박막을 제작하여 버퍼층 종류(Fe, Cu, Cr, Ta)와 두께, 비자성층인 Cu두께 변화에 관한 자기저항비의존성을 조사하였다. 또한 이들 시료에 대하여 열처리를 행한 후 열처리가 이 시료의 구조, 자기적 성질 및 자기저항에 미치는 영향을 조사하였다. Fe버퍼층의 두께가 60Å일 때 극대 자기저항비가 14%인 자기저항이 관찰되었고 Fe버퍼층과 Cr버퍼층을 갖는 시료를 비교한 경우 자기저항비는 그다지 차이가 없으나 Fe버퍼층이 있는 경우에 더 큰 포화자기장 및 자기 이력현상을 나타내었다. 250℃까지의 시료에 대한 열처리는 다층박막의 주기성을 유지한채 더 큰 결정립을 갖게 하여 자기저항비는 증가하였으나 그 이상의 온도에서는 계면 혼합 및 계면 확산에 의한 감소를 나타내었다. Giant magnetoresistance (GMR) and magnetic properties of CoFe/Cu multilayers prepared by dcmagnetron sputtering has been studied. We investigated the effect of Fe buffer layer thickness, different buffer layers, and annealing condition on GMR. For the 60Å Fe buffer layer thickness, maximum MR ratio 14% was found. When we have used different buffer layers, multilayers with Cr and Fe buffer show similar GMR magnitude, but multilayers with an Fe buffer have much higher saturation fields and hysteresis. The study of the dependence of the MR behaviors on annealing temperature, the MR ratio was increased to 250℃, but reduced at the temperature higher than 300℃ because of the interfacial diffuse.