Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 27: Poster Session I (Methods: Scanning probe techniques; Methods: Atomic and electronic structure; Methods: Molecular simulations and statistical mechanics; Oxides and Insulators: Clean surfaces; Oxides and Insulators: Adsorption; Oxides and Insulators: Epitaxy and growth; Semiconductor substrates: Clean surfaces; Semiconductor substrates: Epitaxy and growth; Semiconductor substrates: Adsorption; Nano- optics of metallic and semiconducting nanostructures; Electronic structure; Methods: Electronic structure theory; Methods: other (experimental); Methods: other (theory); Solutions on surfaces; Epitaxial Graphene; Surface oder interface magnetism; Phase transitions; Time-resolved spectroscopies)

O 27.31: Poster

Dienstag, 24. März 2009, 18:30–21:00, P2

(SP)VLEED: A spin-polarized very-low-energy electron-diffraction experiment — •Kathrin Wulff, Ulrich Burgbacher, Anke B. Schmidt, and Markus Donath — Physikalisches Institut, Westfälische Wilhelms-Universität Münster

The shape of the surface-barrier potential at conductive surfaces dictates the appearance and spin dependence of surface states. Currently, parameterized polynomials are incorporated in theoretical calculations to connect the Coulomb-like asymptotic regime far from the surface to the bulk muffin-tin zero. In intensity versus energy profiles I(V) of elastically scattered electrons fine structures appear, which are sensitive to the shape of the surface-barrier potential [1]. So far, spin-polarized low-energy electron-diffraction measurements on W(100) have already shown a strong spin dependence of the I(V) profiles due to spin-orbit interaction [2].

We present a new experimental setup for spin-polarized very-low-energy electron-diffraction (SP-VLEED) measurements to investigate the spin dependence of the surface-barrier potential of ferromagnets. Spin-polarized electrons emitted from a GaAs photocathode are directed onto the sample with a variable angle of incidence and with energies in the range of 0 to 50 eV. The specular reflected intensity is measured as a function of the primary-electron energy with a retarding field analyser. To access certain crystallographic axes, the sample can be rotated around an azimuthal axis.

[1] R.O. Jones, P.J. Jennings, Surf. Sci. Reports 9 (1988) 165.
  [2] E.G. McRae, D.T. Pierce, Phys. Rev. B 24 (1981) 4230.