Correlations between structure and magnetism in thin films and nanostructures

The bidimensionnal character of thin magnetic films deposited on single-cry stal substrates, together with the occurrence of singular crystallographic structures, often confer on these systems electronic properties that cannot be found in bulk solids. For example, thin Ni layers deposited on Cu(001) present a perpendicular magnetic anisotropy in a very wide thickness range. We will show that this can be explained by a distorted structure of Ni, or iginating from the strain induced by the epitaxy on the Cu substrate. In th is field of 2D magnetism, nanostructures are now investigated. Thin Fe laye rs on MgO(001) were cut into stripes by the "atomic saw" method: a compress ion of the substrate induces a dislocation slipping which saws both the sub strate and the Fe film in regular and separated ribbons. The observed perpe ndicular to the stripes magnetization easy axis will be explained by a stru ctural relaxation occurring during the structuration process. In these two studies, a precise structural characterization and simple magnetoelastic mo dels allow one to describe the magnetic behaviors of these systems.