EPITAXIAL FERROMAGNETIC MNAS THIN-FILMS GROWN BY MOLECULAR-BEAM EPITAXY ON SI(001) SUBSTRATES

We have grown ferromagnetic MnAs thin films on Si(001) substrates by molecular beam epitaxy. Epitaxial monocrystalline MnAs films with the growth plane of((1) over bar 1101) were obtained when the Si surface was first exposed to an As-4 flux and then Mn and AS(4) fluxes Were codeposited. It was found that the very first monolayer of As on Si(001) plays an essential role to obtain epitaxial MnAs thin films. Magnetization measurements indicate that the easy axis of the MnAs thin films is in-plane, along the [<(11)over bar>20] of MnAs and the [110] of Si, normal to the substrate misorientation. The M-H curve of a 300-nm-thick film shows a hysteresis with a saturation magnetization M(s) of 694 emu/cm(3) and a coercive field H-c of 94 Oe, when the magnetic field is applied along the easy axis. (C) 1995 American Institute of Physics.