The growth dynamics of submonolayer coverages of Cobalt during buffer layer assisted growth on Ag(111) and Pt(111) substrates is investigated by variable temperature scanning tunneling microscopy in the temperature range between 80 and 150 Kelvin. It
is found that attractive cluster-substrate interactions can govern the cluster formation on the Xe buffer layer, if the Xe layer is sufficiently thin. The interpretation of the microscopy results are supported by x-ray magnetic circular dichroism which monitors the effect of cluster-substrate interactions on the formation of magnetic moments and magnetic anisotropy of Co nanocluster during the different stages of growth. {it Ab-initio} calculations show that the cluster magnetism is controlled by the interface anisotropy, leading to perpendicular magnetization for Co on Pt(111). Limits of and new potential for nanocluster fabrication by buffer layer assisted growth are discussed.
The domain wall induced reversal dynamics in compressively strained GaMnAs was studied employing the magneto-optical Kerr effect and Kerr microscopy. Due to the influence of an uniaxial part in the in-plane magnetic anisotropy (90+/-Delta) domain wal
ls with considerably different dynamic behavior are observed. While the (90+Delta) reversal is identified to be propagation dominated with a small number of domain walls, the case of (90-Delta) reversal includes the nucleation of many domain walls. The domain wall nucleation/propagation energy for both transitions are estimated using model calculations from which we conclude that single domain devices can be achievable using the (90+Delta) mode.
