Department of Chemistry, University of Florence, Italy
Friday, March 18, 2022
Organometallic sandwich complexes of paramagnetic lanthanides ions are currently the focus of great interest because of the observation that dysprosium(III) derivatives present magnetic hysteresis of molecular origin, i.e. Single-Molecule Magnet behavior, above liquid nitrogen temperature.
Sandwich complexes of early transition metal ions such as Ti and V carrying one unpaired electron are also well known but their spin dynamics are not equally investigated. In our search for highly coherent and evaporable magnetic molecules as potential molecular spin qubits, we identified titanium(III) and vanadium(IV) as promising candidates.
Pulsed EPR investigations have revealed that the coherence times reach ca. 35 ms at low temperature in frozen deuterated toluene of these hydrogen-rich molecules. Similar coherence times are also observed when fluorenyl replaces the Cp ligand. Ab initio calculations revealed that the low energy vibrational modes involving the rotation of the rings have a weak spin-phonon coupling, while hydrogen atoms are placed within the frozen sphere, thus not too detrimental for decoherence.
These small neutral molecules have been evaporated and deposited on different metallic substrates, including lead as a typical superconductor. Their properties have been investigated by STM and synchrotron-based techniques to reveal complex adsorption geometries that affect the level of hybridization with the underlying substrate.