EPITAXIAL ORIENTATION AND MAGNETIC-PROPERTIES OF MNAS THIN-FILMS GROWN ON (001) GAAS - TEMPLATE EFFECTS

We have studied template effects in molecular beam epitaxy (MBE) of fe rromagnetic MnAs thin films on (001) GaAs substrates. When As2 flux wa s first supplied without Mn flux on the (001) GaAs prior to the MnAs g rowth, the surface reconstruction was disordered c(4 x 4), a more As-r ich surface than c(4 x 4). The growth direction of the MnAs thin film grown on this surface is [1BAR100] and the easy magnetization axis was found to be along the [1BAR1BAR20] of MnAs and the [110] of GaAs. In contrast, when one monolayer of Mn was first deposited on the c(4 x 4) GaAs surface and then As2 flux was supplied to grow MnAs, the growth direction of the MnAs thin film was found to be mainly [1BAR101], and the easy magnetization axis was along the [1BAR1BAR20] of MnAs and the [1BAR10] of GaAs, 90-degrees different with respect to the substrate. These results indicate the importance of the very first monolayer in controlling the epitaxial orientation and magnetic properties of epita xial ferromagnetic MnAs thin films. (C) 1994 American Institute of Phy sics.