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Light-induced molecular spin switch on surfaces

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INTERNSHIP + PHD
Internship director : Amandine Bellec
e-mail : amandine.bellec@univ-paris-diderot.fr
Phone number : 01 57 27 62 90
Funding : YES       type of funding : European project
Techniques to be used : ultra-high vacuum setup, synchrotron radiation, low temperature scanning tunneling microscopy and spectroscopy.
Required qualities : excellent studies, taste for experimental research, teamwork attitude.

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. The ultimate goal would be the control of the molecule/ferromagnetic interface properties by external means such as light. 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]. 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 internship, which can be followed by a PhD, is to create reliable molecule/ferromagnetic interfaces which can be controlled by light and to investigate their structural, electronic and magnetic properties. To do so, FeII spin crossover molecules will be used. The formation of long-range ordered mixed spin-state structure on Au(111) raises questions on the importance of the substrate nature. Experiments with other substrates such as copper, cobalt or graphene will be realized by scanning tunneling microscopy in a first step. The possibility to illuminate the tunnel junction will be implemented. In longer terms, magneto-optic and X-ray measurements such as absorption spectroscopy or grazing incidence diffraction will be considered.

[BAI16] K. Bairagai et al., Nat. Commun., 7, 12212 (2016)

Internship/PhD spin-crossover molecules on surfaces