Influence of Substrate Surface Reconstruction on the Growth and Magnetic Properties of Fe on GaAs(001)
NAVAL RESEARCH LAB WASHINGTON DC
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We have studied the magnetic and structural properties of epitaxial bcc Fe001 films grown at 175 C on molecular-beam epitaxy-prepared GaAs001-24 and -c44 reconstructed surfaces, with film thicknesses ranging up to 30 ML 43 . We present measurements of the thickness-dependent evolution of the magnetic properties of the Fe films as determined by in situ magneto-optic Kerr effect. We find that the magnetic properties and growth mode are similar for both 234 and c434 reconstructions, although the initial adsorption sites and island nucleation as measured by scanning tunneling microscopy are clearly dominated by the substrate surface reconstruction. The onset of room-temperature ferromagnetism occurs at 6 ML for growth on both GaAs surface reconstructions. At this coverage, the measured Curie temperature 100 C is significantly reduced from that of bulk alpha-Fe 770 C. The anisotropy is dominated by a uniaxial component such that the two 110 axes are inequivalent for all coverages studied. Shape anisotropy does not appear to play a significant role.
- Inorganic Chemistry
- Physical Chemistry