Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 28: Surface Magnetism
MA 28.8: Vortrag
Donnerstag, 29. März 2007, 17:00–17:15, H23
Two-dimensional antiferromagnetism of the Co monolayer on W(001) — •Paolo Ferriani1, Andre Kubetzka1, Stefan Heinze1, Matthias Bode1, Gustav Bihlmayer2, Stefan Blügel2, Kirsten von Bergmann1, Oswald Pietzsch1, and Roland Wiesendanger1 — 1Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg — 2Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich
The technological call for smaller devices boosted nanomagnetism. In surface magnetism, this led to the study of magnetic materials at mono- and submonolayer coverages. In this regime, the effect of the adjacent substrate on the magnetic properties can become crucial. E.g., it has been lately found that one monolayer (ML) Fe, the prototypical ferromagnet (FM), surprisingly exhibits antiferromagnetic (AFM) order on W(001) [1]. An even more complex nanoscale magnetic structure was discovered for the Fe ML on Ir(111) [2]. The question arises whether the magnetic order of other ferromagnetic metals can be changed as well if their ML is grown on strongly hybridizing substrates.
Here we give strong evidence of unexpected AFM order for 1 ML Co/W(001) by a combination of ab-initio calculations and scanning tunneling microscopy. The electronic structure close to the Fermi level of 1 ML Co/W(001) prevents a direct imaging of the AFM state, at variance with 1 ML Fe/W(001) [1]. However, the dI/dU spectrum and the dispersion of a surface state extracted by dI/dU maps of standing wave patterns fit the theoretical results for the AFM state, but not for the FM one. [1] A. Kubetzka et al., Phys. Rev. Lett. 94, 087204 (2005) [2] K. von Bergmann et al., Phys. Rev. Lett. 96, 167203 (2006).