SINGLE-MOLECULE-MAGNET (SMM) BEHAVIOUR IN URANIUM COMPOUNDS

Uranium complexes are unique counterparts to the lanthanides in order to understand single ion magnet behaviour and possible applications in quantum computing and spintronics. Aiming at contributing to a better description of the magnetic ground state and to separating the role of uranium and the radical ligands in the SMM behaviour of these systems, different approaches using spectroscopic (FIR and HF-EPR) and theoretical investigations have been employed. An X-ray magnetic circular dichroism (XMCD) study at ESRF beamline ID12 was performed for six uranium compounds, 3 based on hydrotris (3,5-dimethylpyrazolyl)borate (Tp^Me2) and other 3 based on trisamido-1,4,7-triazacyclononane [(SiMe₂NPh)₃-tacn]. Low temperature experiments at the M_4,5-edge of uranium made possible to test and confirm the existing magnetic results and successfully deducing the spin and the orbital magnetic moment carried by the U-5f states. This separation of contribution is of paramount importance to understand the SMM behaviour of these compounds.