Change of magnetic property in ultrathin Fe films grown on Pd(1 1 1) induced by morphological change and interdiffusion

We have studied the magnetic and structural properties of ultrathin Fe films grown on a Pd(1 1 1) substrate using in situ surface magneto-optic Kerr effect (SMOKE), X-ray photoelectron spectroscopy (XPS), and low energy electron diffraction (LEED). SMOKE measurements show that perpendicular magnetic anisotropy was partially induced by post-annealing at 450 K for a 2.0 ML (monolayer, ML) film. For thicker (2.5 and 5.5 ML) films, a strong enhancement of the Kerr signal was observed upon post-annealing at temperatures above 600 K. Underlying reasons, such as morphological change and interdiffusion of Fe atoms into the Pd substrate, are discussed on the basis of the XPS and LEED results.