Determination of the Infrared Complex Magnetoconductivity Tensor in Itinerant Ferromagnets from Faraday and Kerr Measurements

We present measurement and analysis techniques that allow the complete complex magnetoconductivity tensor to be determined from mid-infrared (11-1.6 {micro}m; 100-800 meV) measurements of the complex Faraday ({theta}{sub F}) and Kerr ({theta}{sub K}) angles. Since this approach involves measurement of the geometry (orientation axis and ellipticity of the polarization) of transmitted and reflected light, no absolute transmittance or reflectance measurements are required. Thick-film transmission and reflection equations are used to convert the complex {theta}{sub F} and {theta}{sub K} into the complex longitudinal conductivity {sigma}{sub xx} and the complex transverse (Hall) conductivity {sigma}{sub xy}. {theta}{sub F} and {theta}{sub K} are measured in a Ga{sub 1-x}Mn{sub x}As and SrRuO{sub 3} films. The resulting {sigma}{sub xx} is compared to the values obtained from conventional transmittance and reflectance measurements, as well as the results from Kramers-Kronig analysis of reflectance measurements on similar films.