Origin of magnetic anisotropy of functionalised iron oxide nanoparticles : an EXAFS investigation

The objective of this proposal is to obtain a definite answer about the coordination modes of different molecular complexes at the surface of small iron oxide nanoparticles. Indeed, the decorated Fe2O3 magnetic nanoparticles exhibit enhanced and finely tuneable magnetic anisotropy, responsible for their efficiency in magnetic hyperthermia or data storage, for example. Nevertheless, different behaviours have been observed on previous magnetism analysis at the L-edges of heteroatoms that decorate the nanoparticles surface, namely Co(II), Zn(II) and MN(II). We hypothesised that the anchoring sites at the nanoparticles surface (either on octahedral or tetrahedral sites) are responsible for such anisotropy modifications. The expected results would help understanding the specificity of coordination sites of these different atoms on the iron oxide and would help explaining the origin of the magnetic anisotropy variations.