MCDAD investigation to characterize the magnetic behavior of thin Pd films on Co(0001)

Abstract

The magnetic characteristics of Pd thin films on Co(0001) were investigated by means of Magnetic Circular Dichroism in the Angular Distribution of photoelectrons (MCDAD). For uncovered Co it was found that significant photoelectron intensity differences occur for electrons emitted from the 3d band near the Fermi level in the situation of a fixed helicity of the incoming circularly polarized radiation and opposite magnetization of the magnetic layer.After deposition of Pd in the submonolayer regime up to a thickness of a few layers, the new features which are present in the photoemission spectra exhibit asymmetries, too. A strong hybridization takes place at the interface which is due to the intermixing of Pd 4d and Co 3d states. This interface state shows no dispersion and nearly no change of the asymmetry value for different photon energies. Additionally, the sign of the asymmetry is opposite to that of the ferromagnetic substrate. The reason is the strong hybridization which results not in a rigid band shift as found for less-interacting adsorbates but in new states being different in the majority and minority spin band. As a consequence, the interface layer exhibits an induced magnetic polarization. The structure near the Fermi energy exhibit the same sign of the asymmetry but with lower values. For a thickness of more than 2 monolayers the spectrum is comparable to bulk measurements and shows no MCDAD asymmetries in the entire binding energy region.