Surface localized nitrogen incorporation in epitaxial FePd films and its effect in the Magneto-Optical properties

In situ exposure of FePd chemically disordered alloys to a N plasma prior to capping layer deposition produces a nitridation localized on the topmost 20 Å alloy region. In this region, a N–Fe bond prevails over the N–Pd. From the structural point of view, this nitridation does not induce relevant modifications on the lattice parameters compared with non-nitrided samples of equivalent composition, being only slightly modified in the alloys with higher Fe concentration. From the magnetic point of view, nitrogen incorporation induces a reduction or even a loss of the ferromagnetism of the nitrided FePd region, giving rise to a global decrease in the polar Magneto-Optical Kerr response in a wide spectral range due to the increase of the effective thickness of the non-magnetic capping layer.