Emergence of Spinmerism for Molecular Spin-Qubits Generation

Abstract: Molecular platforms are regarded as promising candidates in the generation of units of information for quantum computing. Herein, a strategy combining spin-crossover metal ions and radical ligands is proposed from a model Hamiltonian first restricted to exchange interactions. Unusual spin states structures emerge from the linkage of a singlet/triplet commutable metal centre with two doublet-radical ligands. The ground state nature is modulated by charge transfers and can exhibit a mixture of triplet and singlet local metal spin states. Besides, the superposition reaches a maximum for $2K_M = K_1 + K_2$, suggesting a necessary competition between the intramolecular $K_M$ and inter-metal-ligand $K_1$ and $K_2$ direct exchange interactions. The results promote \textit{spinmerism}, an original manifestation of quantum entanglement between the spin states of a metal centre and radical ligands. The study provides insights into spin-coupled compounds and inspiration for the development of molecular spin-qubits.