Surface structure of MBE-grown α-Fe2O3(0001) by intermediate-energy X-ray photoelectron diffraction

We have used intermediate-energy X-ray photoelectron diffraction to determine the surface structure of epitaxial alpha-Fe2O3(0001) grown on alpha-Al2O3(0001). Comparison of experiment with quantum mechanical scattering theory reveals that the surface is Fe-terminated, and that the first four layer spacings are -41, +18, -8, and 47% of the associated bulk values, respectively. These results agree reasonably well with the predictions of molecular mechanics and spin-density functional theory previously reported in the literature for the Fe-terminated surface. However, we find no evidence for an O-terminated surface predicted to be stable by spin-density functional theory. (C) 1999 Elsevier Science B.V. All rights reserved.