Epitaxial ferromagnetic MnAs thin films grown by molecular beam epitaxy on Si (001) substrates

Abstract

We have grown ferromagnetic MnAs thin films on Si(001) substrates by molecular beam epitaxy. Epitaxial monocrystalline MnAs films with the growth plane of (1̄101) were obtained when the Si surface was first exposed to an As4 flux and then Mn and As4 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 [1̄1̄20] 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 Ms of 694 emu/cm3 and a coercive field Hc of 94 Oe, when the magnetic field is applied along the easy axis.