P. A. Montano

Leed measurements of Fe epitaxially grown on Cu(100)

Abstract Iron was epitaxially grown on a Cu(100) surface. Low energy electron diffraction (LEED) intensity versus energy curves were recorded for 1 and 10 layers of iron on Cu(100) at room temperature. A full dynamical analysis was performed using the renormalized forward scattering perturbation method. The surface Debye temperatures were determined to be 233 K for 1 ML Fe and 380 K for 10 layers of Fe. The value obtained for fcc iron was 550 K. A multiple relaxation approach was employed in analyzing the experimental data. The estimated interlayer spacings for the first and second layers were 1.78±0.02 A (first) and 1.81±0.02 A (second) for 1 ML Fe, and 1.81±0.02 A (first) and 1.78±0.02 A (second) for 10 layers of Fe on Cu(100). Auger electron spectroscopy was used to determine the thickness of the Fe films, and the LEED measurements indicate approximately a layer-by-layer growth until about 17 layers at room temperature. At higher temperatures there is evidence of iron diffusion or copper surface segregation.

LEED measurements of one monolayer of iron epitaxially grown on Cu(111)

Abstract We report a LEED study of Cu(111) and one monolayer of iron epitaxially grown on Cu(111). A full dynamical analysis was performed using the renormalized forward scattering method. We studied the influence of the scattering potential employed on the quality of the LEED theoretical analysis. The analysis of the intensity versus energy for all the spots at room temperature gave a 2% contraction for the topmost layer of Cu(111) and 3% contraction for one monolayer of iron (in reference to Cu(111) bulk). We also detected Cu surface segregation at relative low temperatures (473 K) for iron epitaxially grown on Cu(111). Time and temperature play a significant role in the surface segregation process. Great care must be exercised when studying the electronic and magnetic properties of epitaxially grown fcc iron on Cu(111) when samples are prepared above room temperature.

Leed study of Fe epitaxially grown at 190°C on Cu(100)

Abstract We report a LEED study of iron deposited on Cu(100) at 190°C. Very sharp LEED patterns were obtained for high iron coverages. We observed evidence of an ill defined Fe/Cu interface for one monolayer of iron deposited at 190°C. The stability of the iron overlayers was tested as a function of time for various coverages. For one monolayer the intensity versus energy curve for the (00) beam shows time dependence at 190°C. For four layers, no significant changes were observed in the LEED spectra over a period of one hour. We measured for five layers of iron a top layer expansion of 2.8% relative to the bulk. The interplanar spacing for bulk fcc Fe at 190°C remains equal to the room value. In these experiments the samples were deposited at 190°C and kept at this temperature during the LEED measurements.

Surface electronic behavior of face-centered-cubic iron on copper

We have studied the electronic structure of fcc iron grown epitaxially on (100) copper with ultraviolet photoemission (UPS), surface magneto‐optic Kerr effect (SMOKE), low‐energy electron diffraction (LEED), and self‐consistent film linearized muffin‐tin‐orbital (FLMTO) calculations. This study identifies and explains novel characteristic UPS features of fcc iron and a substantial change in the work function compared to bcc iron. The SMOKE measurements show that fcc iron grown on copper has two metastable states lying close in energy. One of these is not ferromagnetic and occurs at room temperature, while the other is ferromagnetic and occurs at 190 °C. As shown by LEED, the ferromagnetic state has an expanded surface interplanar lattice; and UPS shows exchange splittings in that state.