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O: Fachverband Oberflächenphysik

O 32: Surface or interface magnetism

O 32.8: Vortrag

Mittwoch, 25. März 2009, 12:15–12:30, SCH A315

Correlation between morphology and magnetism of Ni films on adsorbate modified Cu(110) — •Mariella Denk, Richard Denk, Michael Hohage, Lidong Sun, and Peter Zeppenfeld — Institut für Experimentalphysik, Johannes Kepler Universität Linz, A-4040 Linz, Austria

We have investigated the growth and magnetism of thin Ni films evaporated on adsorbate modified Cu(110) in situ and under UHV conditions. In particular, we used Cu(110)-(2×1)O, Cu(110)-c(6×2)O, and Cu(110)-(2×3)N as substrates. In all cases the adsorbates (O, N) were found to float on top of the Ni film, acting as surfactants. Combining complementary methods like STM and Reflectance Difference Spectroscopy (RDS), as well as utilizing the sensitivity of RDS to the polar Magneto-Optic Kerr Effect (RD-MOKE), structural and magnetic properties have been probed simultaneously. For nickel grown on Cu(110)-(2×1)O we find an extremely sharp reversal of the magnetic easy axis from in-plane to out-of plane at 9 ML, while for the growth on Cu(110)-c(6×2)O the transition takes place at slightly higher coverages (10 ML), apparently due to a rougher Ni film. However, for growth on Cu(110)-(2×3)N no switching of the easy axis to out-of plane has been observed, even though the film roughness and morphology is similar as in the Cu(110)-c(6×2)O case. Thus, the termination by O or N of the Ni film is crucial for the magnetic properties. Indeed, oxygen exposure during the growth of Ni on Cu(110)-(2×3)N leads to a partially O-terminated Ni film and to the appearance of out-of plane ferromagnetism.