Mn-X-Bi系 薄膜의 磁氣-光學的 特性 = Magneto-optic Properties of Mn-X-Bi Thin Films

다국어 초록 (Multilingual Abstract)

Magnetic and mageto-optic properties of the ferromagnetic compound Mn_5Ni_2Bi_4 thin films are studied. The films are prepared by vacuum evaporation. Bi, Ni and Mn films are evaporated successively onto glass substrates at room temperature. The experimental conditions of the evaporatina process and thermal treatment of thin films of the Mn-Ni-Bi tennary system are examined. The specific conditions required are obtained to be more than ten hours of annealing at 350℃ in vacuum of 10^-5∼10^-6 Torr. The formation of compound Mn_5Ni_2Bi_4 films was confirmed by X-ray diffraction.
The magnetic hysteresis loop of Mn_5Ni_2Bi_4 films of the thickness 800 A˘ measured by a magneto-optical method are rectangular, that is, the remnant magnetization equals the saturation magnetization.
The magneto-optic Kerr effect of the films are inverstigated 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 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 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 5000∼5200A˚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 Mn_5Ni_2Bi_4 film are smaller than those of MnBi. The films are very resistant to oxidation by the surrounding atmosphere. The Mn_5Ni_2Bi_4 film seems promising as a magneto-optic memory medium