• Title/Summary/Keyword: magneto-optic

Search Result 86, Processing Time 0.023 seconds

Relation Between Magnetization Easy Axis and Anisotropic Magnetoresistance in Permalloy Films (퍼멀로이 박막의 자화 용이축과 자기저항 변화와의 상관관계에 대한 연구)

  • Hwang, Tae-Jong;Ryu, Yeung-Shik;Kwon, Jin-Hyuk;Kim, Ki-Hyeon;Kim, Dong-Ho
    • Journal of the Korean Magnetics Society
    • /
    • v.18 no.1
    • /
    • pp.28-31
    • /
    • 2008
  • We studied the effect of easy magnetization axis orientation with respect to the strip direction by measuring the magnetoresistance(MR), the magneto-optic Kerr effect(MOKE), and real-time domain evolution. The five strips were patterned on a single chip with the easy axis orientation of each strip relative to the longitudinal direction by around $0^{\circ}$, $18^{\circ}$, $36^{\circ}$, $54^{\circ}$ and $72^{\circ}$, respectively. The overall shape of field dependent MR was mostly governed by the anisotropy magnetoresistnace. The relative change of the longitudinal MR was significantly increased with increasing angle between the easy axis and strip direction, whereas, the transverse MR variation rate was decreased with increasing angle. Several MR steps were observed during the magnetization reversal, and the simultaneous measurement of the MOKE and the domain images identified that the MR steps were associated with evolution of the oppositely directed magnetic domain.

Measurement of magnetic kerr rotation and faraday fotation angles by polarization modulation method (편광 변조 방법에 의한 자기 Kerr 회전각 및 Faraday 회전각 측정)

  • 이용호;이상수;이용호
    • Korean Journal of Optics and Photonics
    • /
    • v.3 no.2
    • /
    • pp.105-110
    • /
    • 1992
  • In order to measure fine rotation angles by magneto-optic effects of magneto-optical recording thin films, a polarization modulation method is used. In the experiment, the polarization of laser (He-Ne laser) beam is modulated by a Faraday rotator and the amplified modulated signals are selectively detected by phase sensitive detector. The magnetic Kerr rotation and Faraday rotation hysteresis loops are investigated by this method for thermally evaporated amorphous TbFeCo thin films and RF sputtered garnet thin films. Rotation angles about $0.25^{\circ}$ are measured easily from TaFeCo thin films. In the case of longitudinal Kerr rotation, very small rotation angle of $2.5\times10^{-3^\circ}$ is measured with good accuracy of the measurement (about $1\times10^{-3^\circ}$). And it is found that each thin films have the hysteresis curves of high coercivity and good squareness.

  • PDF

Magnetic and Magneto-Optical Properties of $Mn_{1-x}Cr_xPt_3$ Ordered Alloy Films ($Mn_{1-x}Cr_xPt_3$ 박막의 자기 및 자기광학 특성)

  • 박문기;조재경
    • Journal of the Korean Magnetics Society
    • /
    • v.8 no.6
    • /
    • pp.374-379
    • /
    • 1998
  • $Mn_1-xCr_xPt_3$ alloy films have been prepared by depositing (Mn, Cr)/Pt multilayers using a rf magnetron sputterer followed by heat treatment. Small and wide angle x-ray diffractometry, magnetic hysteresis loops and Kerr rotation angle spectra of the films have been measured and used to investigate structural, magnetic and magneto-optic properties of the films. The films had a crystal structure of ordered AuCu$_3$ type and the strong preferred orientation of a (111)plane parallel to the film surface. The saturation magnetization of the films was decreased with Cr content reaching almost zero near x=0.58 and then increased for further increasement of Cr content up to x=0.77 over that stayed almost constant. This indicated that Cr atoms were antiferromagnetically coupled with Mn atoms. The magnetic easy axis of MnPt$_3$(x=0) film was parallel to the film surface but those of the films with x$\geq$0.58 increased as Cr content increased reaching about 4 kOe at x=1(CrPt$_3$). The dependence of the Kerr rotation angle on the Cr content was similar to that of the saturation magnetization on the Cr content. The films with x=0.77 and x=1 showed the larger Kerr rotation angle at the wavelengths of near infrared compared to the magneto-optic recording medium, TbFeCo, currently being used.

  • PDF

A Study on the Current Sensor Using an Optical Modulator with BSO (BSO와 ZnSe를 광 변조기로 이용한 전류센서에 관한 연구)

  • 김요희;이대영
    • Journal of the Korean Institute of Telematics and Electronics A
    • /
    • v.28A no.9
    • /
    • pp.721-728
    • /
    • 1991
  • In this paper, a magneto-optic modulator has been designed by using single crystal BSO and polycrystal ZnSe as Faraday cells. And practical core-type optical current sensors using pure iron and permalloy have been prepared and experimented. In order to obtain efficient magnetic field detection, LED(NEC OD08358, 0.87 $\mu$m) was used as optical source, PIN-PD(OD-8454)as optical receiver and multi-mode optical fiber (100/140$\mu$m) as transmission line. The characteristics matrix of the optical element was calculated by Stokes parameter, and optic modulation characteristics equations were derived by Muller matrix. Electromagnetic analysis program (FLUX 2D, micro VAX 3600) by finite element method was used to find the magnetic flux density around the core. The measuring error of the output voltage to input current has been masured below 5% in the range of 50A to 1000A. As the temperature was changed from -20$^{\circ}C$ to 60$^{\circ}C$, the maximum measurement error of the optical output has been found to be 0.5% at 60$^{\circ}C$. These experimental results show good temperature and linearity characteristics. The SNR of the overall system was 47dB in case of 600A (250.2 Oe) conductor current and the system has good noise immunity.

  • PDF

Annealing Temperature Dependence of Magnetic and Optic Properties of Bi:YIG Films Deposited with Aerosol Deposition Method

  • Shin, Kwang-Ho;Mizoguchi, Masahiko;Inoue, Mitsuteru
    • Journal of Magnetics
    • /
    • v.12 no.3
    • /
    • pp.129-132
    • /
    • 2007
  • Bismuth-substituted yttrium iron garnet (Bi:YIG, $Bi_{0.5}Y_{2.5}Fe_5O_{12}$) films were deposited with aerosol deposition method and their magnetic and optical properties were investigated as a function of annealing temperature. Since the ceramic films deposited with aerosol deposition method have not a perfect crystal structure due to non-uniform internal stress occurred by mechanical collision during their deposition, the post annealing could be a key process to release its internal stress and to improve its micro structure for optimizing the magnetic and magneto-optic properties of films. The crystallinity of Bi: YIG film was improved with increase of annealing temperature, and the saturation magnetization increased up to 87 emu/cc at $800^{\circ}C$. The Faraday rotation increased up to $1.4deg/{\mu}m$ by annealing at $700^{\circ}C$ around the wavelength of $0.5{\mu}m$. The optical transmittance of the Bi:YIG film was also improved in visible region.

Fabrication and Optical Characterization of Highly Dy3+-ion-incorporated Alumino-borosilicate Glasses for Magneto-optical Applications at 1550 nm (1550 nm 자기광학 응용을 위한 고농도 Dy3+ 이온이 함유된 알루미노보로실리케이트 유리의 제조 및 자기광학 특성 분석)

  • Kadathala Linganna;Yong-Tak Ryu;Young-Ouk Park;Bong-Ahn Yu;Bok Hyeon Kim
    • Korean Journal of Optics and Photonics
    • /
    • v.35 no.3
    • /
    • pp.115-120
    • /
    • 2024
  • Magneto-optical (MO) materials have attracted much attention, since they can be utilized for various optical applications, such as magnetic field sensors, optical current sensors, optical isolators, and optical circulators. In this study, alumino-borosilicate (ABS) glasses with high concentrations of Dy3+ ions were fabricated by a conventional melt-quenching technique, and the dependence of their thermal, optical, and magneto-optical properties on Dy3+ ion concentration was investigated. The MO property of the glasses was investigated by measurement of Faraday rotation at 1550 nm. The Faraday rotation angle increased linearly with the increase of Dy3+ ion concentration in the glasses. A very high Verdet constant of -6.86 rad/(T·m) was obtained for glass with a Dy3+ ion concentration of 30 mol%. In addition, the ABS-Dy glasses showed good thermal stability of greater than 128 ℃ against crystallization, and high optical transmission of 70% in the visible to near-infrared windows of 480-720, 1390-1560, and 1800-2400 nm. Due to the high Verdet constant and good thermal stability, the ABS-Dy glasses in this study could be candidate optical materials for MO device applications at 1550 nm.

Design of the Large Diameter Faraday Rotator for High-power Laser Systems (고출력 레이저 시스템을 위한 대구경 Faraday Rotator 제작)

  • Hong, Sung-Ki;Seo, Young-Seok;Ko, Kwang-Hoon;Kim, Young-Won;Wee, Sang-Bong;Lim, Chang-Hwan
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.57 no.6
    • /
    • pp.1026-1031
    • /
    • 2008
  • We report on the design and experimental results of a large diameter faraday rotator for the high-power laser system(KLF: Kaeri laser facility) that was completed in late 2007s at Korea Atomic Energy Research Institute. The design involves modelling the magnetic field of cylindrical coil with large diameter(110 mm). Magnetic field generation coil is designed by 6 layers using a rectangular wire with cross-sectional area $3{\times}5[mm^2]$. We obtain an isolation ratio for optical feedback of 35 dB at 1064 nm and magnetic field strengths ${\sim}25kG$. We expect that the design can be widely used optical isolators in high-power laser system.

A Study on Simulation Of Readout Signal of Magnet-Optic Disk (광자기 디스크 재생신호 시뮬레이션에 관한 연구)

  • 손장우;조순철;이세광;김순광
    • Journal of the Korean Magnetics Society
    • /
    • v.6 no.3
    • /
    • pp.174-178
    • /
    • 1996
  • A method was studied which simulate signal and noise for magneto-optical disk drive system Recorded mark patterns and incident laser beam were modeled and discretized. Using them readout waveformj and amplitude were simulated. Adding Gaussian random noise to the readout signal and executing one dimensional discrete FFT (Fast Fourier Transform) algorithm signal and noise spectrum was estimated. From the spectrum, CNR (Carrier to Noise Ratio) was obtained.

  • PDF

Magneto-optic effect of thermal evaporated amorphous TbFeCo thin flim (비정질 TbFeCo 합금 증착박막의 자기광학효과)

  • 박용관;양계준
    • Electrical & Electronic Materials
    • /
    • v.5 no.4
    • /
    • pp.439-445
    • /
    • 1992
  • 최근 광자기 기록매체로 주목받고 있는 RE-TM계 비정질 박막을 T $b_{x}$ (F $e_{0.9}$ $Co_{0.1}$)$_{100-x}$ (x=14, 17, 20, 23, 27[at%])의 조성비를 갖는 모합금을 만든후 진공증착방법으로 합금박막을 제작하였다. 각시료의 조성에 따른 자기광학효과를 알아보기 위하여 80K부터 600K에서 포화자화( $M_{s}$ )와 보자력( $H_{c}$)에 대한 온도의존성과 자기이방성상수(Ku), Polar Kerr 이력곡선을 측정하였다. 또한 Curie 온도 근처에서 열처리 시간에 따른 자기 토크 곡선의 변화를 분석 함으로써 합금박막 표면의 산화정도를 정성적으로 평가할 수 있었다. 실험결과 T $b_{22.72}$(F $e_{68.78}$ $Co_{8.5}$)인 시료가 상온에서 8.4KOe의 보자력을 가졌으며 T $b_{x}$(x=23[at%])인 경우가 가장 큰 수직자기이방성을 나타냈다. Polar Kerr 이력곡선은 Tb함량 x=25~26[at%]에서 부호가 반전됨을 알 수 있었다.다.다.다.

  • PDF

A Study on the Wall Mobility of Magnetic Domain for the Singel Crystal $YFeO_3$ ($YFeO_3$ 박판 단결정의 자벽이동에 관한 연구)

  • 김종오;한관희
    • Journal of the Korean Ceramic Society
    • /
    • v.23 no.4
    • /
    • pp.47-54
    • /
    • 1986
  • Since the wall mobility of bubble magnetic materials havin g the large q (q=Kac/2$\pi$$M_s^2$) like a $YFeO_3$ has been found to be proportional to the wall energy theoretically crystallographical direction dependence of wall energy calculated by the basis on the spin configuration of the bubble wall which lies in the ac plane was compared with the crystallographical direction dependence of wall mobility which was measured by the experiment. The sample was a single crystal of $YFeO_3$ which was cut into plate normal to the C axis and polished t a thickness of about 60${\mu}{\textrm}{m}$ The measurement of the wall mobility was carried out by optical system using the magneto-optic Faraday effect. From the good agreement of the crystallographical direction dependence of wall mobility and will energy it was found that the spin configuration of the bubble wall suggested is fair.

  • PDF