Magnétisme, structure et morphologie des films minces de cobalt déposés sur des surfaces vicinales de cuivre Cu(1 1 11) et Cu(1 1 5)

Abstract : Abstract :

Magnetic nanostructures can have properties very different from those of bulk materials. One method to make small objects is to evaporate on a nanostructured substrate like vicinal surfaces with atomic steps. The understanding of magnetic properties of these systems requires a precise determination of their structure and morphology to evaluate the effects of their reduced size and their morphology. We have studied thin cobalt films deposited on Cu(1 1 11) and Cu(115) surfaces by three techniques. Magnetic properties were probed by magneto-optic Kerr effect whereas morphology and cristallographic structure were determined respectively by scanning tunneling microscope and surface EXAFS. The Kerr effects results show an uniaxial magnetic anisotropy with the easy axis along the step edge direction. The anisotropy on the substrate with smaller terraces (Cu(115)) is larger. The STM experiments show an important evolution of the morphology with the quantity of deposited cobalt. Thanks to EXAFS, we evidenced that from 3 monolayers (ML) of cobalt on Cu(1 1 11) and 5 ML on Cu(115), the structure is nearly the same as for Co /Cu(001) i.e. face centered tetragonal and we show that the presence of narrow terraces does not induce any structural anisotropy in the (001) plane. Simulations of magnetic anisotropy which account for missing bonds at the surface and at the step edge (Néel model) and magnetoelastic effects induced by the tetragonalisation show that the uniaxial anisotropy is mainly due to the films morphology and that the structural distortion contribution is very small.
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Contributor : Anne Chaumin Midoir <>
Submitted on : Monday, November 18, 2002 - 2:27:14 PM
Last modification on : Monday, January 2, 2006 - 3:09:25 PM
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Anne Chaumin Midoir. Magnétisme, structure et morphologie des films minces de cobalt déposés sur des surfaces vicinales de cuivre Cu(1 1 11) et Cu(1 1 5). Matière Condensée [cond-mat]. Université Paris XII Val de Marne, 2002. Français. ⟨tel-00001977⟩

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