Influence of the light incidence angle on the precision of generalized magneto-optical ellipsometry

•A brief review of generalized magneto-optical ellipsometry is presented.•We calculate the propagation of uncertainties on the magneto-optical constants.•Decreasing incidence angle increases the uncertainty propagation.•We perform measurements on bulk cobalt films which confirm our predictions.

We study theoretically and experimentally the influence of the light incidence angle φ0 on the precision of generalized magneto-optical ellipsometry (GME). A brief review of the GME methodology is presented together with a study of the error propagation from measurement uncertainties to the precision of the resulting complex index of refraction N and magneto-optical constant Q. The results are compared with longitudinal GME measurements on bulk polycrystalline cobalt. We observe a strong increase of the resulting relative error as φ0 decreases below 45°. We tested our theoretical estimates by performing GME measurements for polycrystalline cobalt (N=2.20+3.42iN=2.20+3.42i; Q=(2.25−0.80i)×10−2Q=(2.25−0.80i)×10−2)) and found GME measurements to clearly exhibit improved reliability for φ0>30°φ0>30°.