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Structural properties of photo-active molecular layer

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Stage et/ou Thèse
Responsables du stage : Amandine Bellec, Yves Garreau, Alessandro Coati
e-mail : amandine.bellec@univ-paris-diderot.fr, yves.garreau@univ-paris-diderot.fr, coati@synchrotron-soleil.fr
Phone number : 01 57 27 62 90 / 62.99
Financement : Ecole doctarale EDPIF       
Techniques utilisées : équipements ultra-vide, diffraction de rayons X en incidence rasante, microscopie et spectroscopie tunnel à basse température.
Qualités requises : très bon niveau, goût pour les expériences, esprit d’équipe.

Organic complexes which are molecules composed of a central metallic atom surrounded by organic ligands are promising objects for the development of new and innovative spintronic devices. Indeed, these complexes having two spin states can be switched from one spin state to the other by external stimuli such as light, pressure or temperature. The incorporation of such materials in actual devices needs a deep understanding of the spin crossover property of molecules on metallic and ferromagnetic surfaces and down to the single molecular level. In this context, we recently demonstrate, by scanning tunneling microscopy measurements, the possibility to induce by light the switching of SCO molecules assembled on a gold surface [BAI16, BAI18]. Surprisingly, the molecules arrange in a long-range ordered structure with molecules in high and low spin states at low temperature. This work, probing the dynamics of the photoinduced switch at the molecular level, was the first proof that SCO is possible for molecules in direct contact with a metallic surface.
The aim of this PhD is to create reliable molecule/ferromagnetic interfaces which can be controlled by light and to investigate their structural properties. To do so, FeII spin crossover molecules will be used. The origin of the long-range ordered mixed spin-state structure, that could be obtained below 80 K, and more importantly the role of the underlying Au(111) single crystal are not yet known. Grazing incidence diffraction measurements at low temperature will be realized to unravel the epitaxial relationship between the molecular layer and the Au substrate. Scanning tunneling microscopy measurements will be realized in parallel to have real space information. Other substrates such as copper, cobalt or graphene will also be investigated in longer term. Practically the internship will take place between MPQ lab in Paris and synchrotron SOLEIL.