Photon energy dependence of the perpendicular geometry magnetic circular dichroism in the 2p3p3p resonant photoemission from Ni

Abstract

The magnetic circular dichroism in the perpendicular geometry of the resonant 2p3p3p photoemission (PE) spectroscopy has been investigated in metallic Ni as a function of the photon energy across the Ni L3 absorption edge. Within the experimental error bars, the photon energy dependence of the PE dichroism signal is the same as the one shown by the magnetic circular dichroism of the corresponding x-ray absorption (XMCD), obtained in the collinear geometry. This is attributed to the fact that, in metal Ni, the orbital Lz and dipolar Tz moments are smaller than the spin angular moment Sz. The latter is the dominating term in both the expressions that give the integrated values of the PE dichroism or XMCD intensities. Although the respective photon energy dependence is very similar, the normalized PE dichroism intensity is a factor ~5.6 smaller than the normalized XMCD signal, while only a factor ~1.6 is expected from theoretical considerations. This factor is observed even below the L3 threshold, thus we exclude that the small intensity of the perpendicular geometry dichroism in the Ni 2p3p3p resonant photoemission is due to fast relaxation processes in the intermediate state.