Structure and magnetism of pulsed-laser-deposited ultrathin films of Fe on Cu(100)

A layer-by-layer growth of ultrathin films right from the beginning would be desirable for establishing a straightforward correlation between magnetism and structure. We give experimental evidence that with the help of pulsed laser deposition (PLD) we can achieve layer-by-layer growth for Fe on Cu(100) in contrast to deposition by molecular-beam epitaxy. We present the results of a comprehensive study of the structural and magnetic properties of PLD-grown ultrathin Fe films of thicknesses between 2 and 10 monolayers (ML) deposited at room temperature. We show scanning tunneling microscopy images and low-energy electron-diffraction (LEED) patterns as well as intensity vs energy $\mathrm{}\left(\mathrm{IV}\right)\mathrm{}$ LEED curves demonstrating that PLD-grown Fe/Cu(100) has an isotropic fcc structure. We characterize the magnetic properties of our films by the magneto-optical Kerr effect. Following the improved growth and morphology, we found strong differences in the magnetic behavior of these films in comparison with Fe thermally deposited onto Cu(100): PLD-grown ultrathin Fe/Cu(100) shows an in-plane easy axis of magnetization in the thickness range 2–5 ML and again from about 10 ML, where the film structure is dominated by the bcc-Fe bulk phase, while there is a perpendicular easy axis of magnetization between 7 and 10 ML coverage. These results are discussed in terms of the different growth and structure due to the characteristic features of the PLD technique.