Strong anisotropy in single atomic layer of Co and Fe on Pt(997)

We explore the magnetic properties of Co and Fe on a Pt(997) vicinal single crystal by means of reflection high energy electron diffraction and the surface magneto-optical Kerr effect. Both Co and Fe are grown at room temperature as wedges with thickness ranging from 0 to 3.5 ML (monolayer). We find that Co and Fe show layer-by-layer growth followed by three dimensional growth as the coverage increases due to the large lattice mismatch. Co and Fe exhibit ferromagnetism down to 0.2 ML coverage due to the strong anisotropy. The symmetry breaking at the surface results in the magnetic easy axis of the atomic layers along the surface normal direction. The coercivity of both Fe and Co atomic layers fit an exponential decay with temperature that can be understood as being due to thermally activated, nonequilibrium spin dynamics. The magnetic anisotropy energy per atom is extracted by fitting the experimental data.