Effects of interfacial structure on the magnetic properties of ultrathin Fe/Pt(111) films with Ag buffer layer

For Fe/Pt(111) grown at 180 K, the easy axis of magnetization changes from out-of-plane to in-plane while the surface structure changes from fcc(111) to bcc(110). The Curie temperature for 1 ML Fe/Pt(111) is close to room temperature. After insertion of submonolayer Ag, no significant change for the Curie temperature is observed. By thermally annealing Ag/Pt(111) at 550 K to form a Ag-Pt surface alloy, we demonstrate that the Curie temperature of the deposited Fe films is elevated to be higher than room temperature. For an ultrathin Fe/Ag/Fe/Pt(111) sandwich system, the strong interaction between the two Fe layers is superior due to the effect of the double Fe/Ag interfaces. This causes that the easy axis of the magnetization switches back to the in-plane direction during the deposition of Fe overlayer on the surface of a Ag/Fe/Pt(111) film.