Crystallographic structure of ultrathin Fe films on Cu(100) - art. no. 086103

We report the observation of bcc-like crystal structures in 2-4 monolayer ( ML) Fe films grown on fcc Cu(100) using scanning tunneling microscopy. The local bcc structure provides a straightforward explanation for their freque ntly reported outstanding magnetic properties, i.e., ferromagnetic ordering in all layers with a Curie temperature above 300 K. The nonpseudomorphic s tructure, which becomes pseudomorphic above 4 ML film thickness, is unexpec ted in terms of conventional rules of thin film growth and stresses the imp ortance of finite thickness effects in ferromagnetic ultrathin films.