Alloy formation in the Co/Pd{111} system — A study with medium energy ion scattering and scanning tunnelling microscopy

The growth and annealing behaviour of ultrathin Co films on Pd{111} have been investigated by medium energy ion scattering and scanning tunnelling microscopy. Incremental annealing of Co/Pd{111} results in intermixing and the formation of an ordered CoPd alloy at 560 K. Under these conditions, MEIS reveals that the top three layers consist of an approximately equimolar mixture of Co and Pd. STM and LEED provide evidence that the overlayer has a p(2 × 1) registry leading to the conclusion that the surface is terminated in the {111} plane of the CoPd L10 structure.