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The magnetism and its correlation with morphology and structure of ultrathin Fe/Cu͑111͒ films have been studied. At room temperature, the films grow in a quasi-one-dimensional form ͑stripes͒ in the submonolayer range. Between 1.4 and 1.8 ML the stripes percolate and become two-dimensional films. The remanent magnetization of the percolated films was observed to be significantly more stable with respect to time than that of the stripes. At low thickness ͑Ͻ2.3 ML͒ the films adopt the fcc structure from the substrate and later transform to bcc͑110͒ structure with Kurdjumov-Sachs orientation. Experimental evidence suggests that the fcc films have a low-spin ferromagnetic or ferrimagnetic phase, and a perpendicular easy magnetization axis. The magnetization switches to an in-plane high-spin phase after the fcc to bcc structural transformation has been accomplished.

The magnetic properties, morphology, and crystallographic structure are studied for Fe films on Cu 3 Au͑100͒ grown at room and low temperature, using in situ magneto-optical Kerr effect, scanning tunneling microscopy, and electron diffraction techniques. At Tϭ160 K a spin-reorientation transition from perpendicular to in-plane magnetization occurs in films with Fe coverages starting from a critical thickness of 3.5 and 5.5 ML for room-temperature and low-temperature growth, respectively. Close to the critical thickness we observe an fcc-bcc structural transformation. The spin-reorientation transition is shown to be correlated to this structural change. This correlation may be explained by a drastic reduction of the perpendicular anisotropy induced by the fcc-bcc structural transformation.

In the search for a correlation between the magnetism and the microstructure of ultrathin films, straightforward layer-by-layer growth is desirable. The thermal deposition of Fe onto Cu(111), however, does not result in this growth mode. In this letter, we compare the initial growth of Fe on Cu(111) prepared by pulsed laser deposition (PLD) with thermally deposited Fe/Cu(111) using scanning tunneling microscopy (STM). In PLD, from the beginning there is two-dimensional nucleation and growth, in contrast to the initial bilayer nucleation and growth found for thermal deposition. Therefore, it is shown by STM that PLD grown films exhibit greatly improved layer-by-layer growth. The different experimental results are interpreted in terms of the very high deposition rate during PLD.