X-ray Kerr rotation and ellipticity spectra at the2pedges of Fe, Co, and Ni

Abstract

We present resonantly enhanced longitudinal magneto-optical Kerr rotation and ellipticity spectra measured across the $2p$ absorption edges of amorphous Fe, Co, and Ni. The Kerr spectra are acquired by a complete polarization analysis of linearly polarized synchrotron radiation upon reflection from the ferromagnetic films. We observe large Kerr rotation angles of up to $\ifmmode\pm\else\textpm\fi{}24\ifmmode^\circ\else\textdegree\fi{},$ more than two orders of magnitude larger than detected in the visible energy range. Spectral contributions stemming from atomic transitions could be separated from interference effects by simulations based on the optical constants, which have been determined through independent experiments. For grazing incidence, we show theoretically and experimentally that the longitudinal Kerr rotation and ellipticity spectra are related to transversal Kerr effect spectra and x-ray magnetic circular dichroism reflection spectra, respectively.