Empty electronic states in magnetic thin films: Fe on Au(100), Ag(100), and Cu(100)

Iron films with thicknesses ranging from 5 to more than 20 monolayers (ML) have been deposited onto Au(100), Ag(100), and Cu(100) and investigated by spin-resolved inverse photoemission spectroscopy. Analysis of surface features corresponding to image states indicates a substrate-dependent overlayer structure and surface quality. Measurements confirm that Fe grows in the bcc phase on Au(100) and Ag(100) and in the fcc phase on Cu(100). Above 15 ML also Fe/Cu(100) films display bcc character. Thick ({}15 ML) bcc films on all the substrates present a remanent in plane magnetization with easy axis along the Fe [010] direction as well as bulklike empty states with majority and minority spin character. Instead, fcc films are not in-plane magnetized. A different behavior of the minority and majority peaks' evolution with film thickness in Fe/Au(100) versus Fe/Ag(100) thin films is also found.