The Growth And Magnetic Properties Of Metal Overlayer Systems: Palladium/copper(100), Iron/aluminum(100) And Iron/sulfur/gallium Arsenide(100)

Epitaxial growth of a metal overlayer on an appropriate substrate can be utilized to create systems which exhibit unique chemical and magnetic properties. This thesis will outline the investigation of three metal overlayer systems: Pd/Cu(100), Fe/Al(100) and Fe/S/GaAs(100). In the Pd/Cu(100) system the growth and evolution of defects were examined using re-emitted positron spectroscopy. Two changes in growth mode were observed: at 0.5 monolayer (representing the completion of the first alloy layer) and 1 monolayer Pd coverages (representing the start of bulk Pd growth). The bulk Pd film was observed to contain 1% vacancy-type defects. In the Fe/Al(100) system the relationship between the overlayer structure and magnetic properties were examined. For Fe coverages {dollar}\u3c{dollar}5 monolayers a disordered, non-ferromagnetic alloy is formed. As further Fe is deposited a poorly ordered, weakly ferromagnetic overlayer is formed. The growth of Fe on GaAs(100) is of considerable industrial interest, but results in the intermixing of As into the Fe overlayer. In this study, S-passivated GaAs(100) was examined as a potential substrate for the growth of Fe overlayers. The use of this substrate was found to successfully prevent the intermixing of As with the Fe overlayer. The resulting Fe overlayer was well ordered and showed strong ferromagnetic behaviour