Oxidized ultrathin Fe films on Cu(001)

We report photoemission studies of ultrathin films of the minority-spin conductor, Fe3O4 on a Cu(001) substrate. Fe films are deposited at room temperature and oxidized at 810 K in 10−6 Torr O2. For Fe films less than 2 ML thick, LEED and STM measurements show that oxidation produces mostly an FeO(111) while thicker Fe layers give Fe3O4(111). Photoemission reveals that there is a distinct electronic structure for these two phases. There are also significant differences between the electronic structures of ultrathin oxide films and those of corresponding bulk oxides.