(Q = S, Se)*

Optically addressable magnetic spins represent a feasible route for designing qubits. Despite significant research progress in the field, large-scale implementation of spin qubits remains challenging attributable to poor control over their interactions. To address this, we study magnetism and luminescence in J = 7/2 Eu₂P₂Q₆ (Q = S, Se) to understand whether and how spin-orbit coupling (SOC) in these materials manifests in their physical properties. Our preliminary data reveal that Eu₂P₂Q₆ systems display a magnetic single-ion behavior while featuring some divergence in their luminescence properties. This can be attributed to the localized-electron magnetism of Eu and the perturbations caused by changing from S to Se, which has larger SOC and spatial extents. To understand the underlying chemistry and physics behind the phenomena, we have performed a series of physical properties characterization such as magnetism, heat capacity, steady-state and time-resolved photoluminescence, and supplemented the results with density functional theory calculations. In this talk, I will share the knowledge gained from this research on how light-matter interactions in Eu-based single-ion magnets can pave a way for controlling qubit initialization and readout.