Photoemission Studies of Magnetic Systems.

I have studied the electronic structure of thin films by photoelectron spectroscopy. My results show that even a monolayer film of Ni/Cu(001) exhibits bulk-like electronic structure and resembles that of bulk Ni. In order to better understand this result, I tracked the sp-band dimension at the Fermi surface of the Ni films for various coverages. For submonolayer coverages of Ni, the sp-band dimension was smaller than that of bulk Cu, but quickly reached that of bulk Ni by 1.2 ML Ni coverage. This continuous decrease implies a charge transfer from the Cu substrate to the Ni film, resulting in a decrease in the filling of the Cu sp-band. This transfer of electronic charge could provide a mechanism for hybridization at the Cu/Ni interface and result in a larger penetration of the film electronic states into the substrate. To quantify the charge transfer, the reverse system of Cu/Ni(001) was studied. Again the sp-band dimension for 45 eV photons was studied as a function of Cu thickness. The change in the sp-band dimension was related to reduced filling in the sp-band of bulk Cu. This corresponded to a reduction of $\sim$0.5 eV in the band-filling of bulk Cu. From the integrated density of states, this was identified to be a charge depletion of $\sim$0.12 electrons/atom for the monolayer film. This shift was observed in core level spectra across the 3p levels, corroborating the assumption