Depression of the Coercive Force via Oxygen Exposure of Ultrathin Fe/Pt(111) Films

The composition and magnetic properties of Fe/Pt(111) after oxygen exposure were investigated. At room temperature the amount of adsorbed oxygen on the surface increased as oxygen exposure also increased until saturation. For Fe/Pt(111) that were thinner than two monolayers, the oxidative process dominated the initial oxygen exposure. In case of thicker Fe, the physical adsorption was more important. Due to the ferromagnetic properties of the iron oxides , the Kerr hysteresis loops experienced a slight change. We estimated that the diffusion length of oxygen atoms into the Fe films were approximately three monolayers. Under saturated oxygen exposure, the formation of iron oxide hindered the formation of ordered Fe-Pt alloys and results in a depression on the coercive force.