Spin Coherence in a Phosphine Oxide-Based Mononuclear YbIII Complex

The implementation of lanthanide-based molecular systems in quantum technologies (QTs) requires an accurate and well-designed environment of the spin-bearing lanthanide ion. Lanthanides have become appealing candidates for QTs given their ability to display both slow magnetic relaxation and quantum coherence, in tandem with other properties, which can be achieved through a rational design of the ligand field. This work covers the characterization of a YbIII compound based on phosphine oxide ligand bis(diphenylphosphino)methane oxide (dppmO2). The compound with a structural formula of [Yb(dppmO2)(NO3)3(H2O)]·CH2Cl2 (1) was structurally characterized through X-ray diffraction techniques. Field-induced slow magnetic relaxation was detected through AC SQUID magnetometry. The spin Hamiltonian parameters were evaluated through both continuous wave (CW) and echo-detected field swept (EDFS) electron paramagnetic resonance (EPR). The field and temperature dependence of the phase memory time (Tm) and spin-lattice relaxation (T1) were determined through Hahn echo decays and inversion recovery pulse sequences, respectively. Strong modulations in the Hahn echo decays were rationalized through coupling to 14N nuclei present in the nitrato donors, while Rabi oscillations show the ability of the system to behave as an effective qubit. Theoretical calculations employed at the DFT and CASSCF/NEVPT2 level were performed to elucidate the electronic structure and magnetic properties of 1.