From molecules to qubits: evolution of single-molecule magnets

Through more than three decades, single-molecule magnets (SMMs) have evolved significantly, progressing from transition-metal clusters with exchange-enhanced high-spin ground states towards lanthanide-based systems characterised by strong spin-orbit coupling and pronounced axial crystal-field anisotropy. The discovery of single-ion magnets and the subsequent realisation of molecular systems further emphasise the magnetic relaxation pathways and enhance quantum coherence. SMMs have emerged as attractive candidates for qubit implementation for practical applications in information storage and spintronics. However, interpreting their quantum properties into robust, scalable device designs remains a major challenge. Hence, a thorough understanding of crystallographic symmetry and its role in governing exchange coupling, magnetic anisotropy, and decoherence mechanisms is vital to revealing the underlying fundamental physics, as these aspects require more attention for next-generation material synthesis to enable next generation practical applications. Here, we discuss the evolution of SMMs and highlight present research gaps and the direction of resolutions for future prospects.