Longitudinal Kerr Magneto-Optic Effect in Permalloy Film

The longitudinal Kerr effect in an evaporated film of nickel (80%) and iron (20%) alloy is investigated by the use of a photoelectric polarization spectrometer. The Kerr rotation of the film is measured as a function of the angle of incidence for several wavelengths of light ranging from 400 mµ to 650 mµ. The compensation of the phase angle of the rotation with which the reflected beam of elliptically polarized light degenerates into a linear polarized light is also made with a Babinet Soleil compensator. When the values of the magneto-optic quantity and the refractive index of the film are chosen as 1.48 × 10 -2 exp { i (32^°)} and 1.76(1-1.84 i ), respectively, at the wavelength 592 mµ, the calculated values of the rotation given by the theory of Voigt agree well with the experimental results.