Single-Molecule Toroic Design through Magnetic Exchange Coupling

The big data era calls for larger capacity of our hard drive, which in turn depends on the number of magnetic units that store bits of 1 or 0. However, as the density of these units increases, flipping one unit without affecting another becomes more difficult because of undesired magnetic perturbations from the reading/writing heads. Single-molecule toroics (SMTs) that exploit vortex-like magnetic structures are insensitive to homogeneous magnetic fields and hence are promising for next-generation ultra-dense information storage. However, the synthesis of such molecular materials is challenging. Here, we show by using ferromagnetic interactions that this target can be realized in a 16-membered heterometallic cluster {Fe₈Dy₈}, which shows a stable 4-fold degenerated magnetic toroidal ground state at low temperatures. This is significantly distinguished from the most studied dipole-dipole interaction-based SMTs and demonstrates a promising strategy for the next generation of SMT design.