An 'Intermetallic' Molecular Nanomagnet with the Lanthanide Coordinated Only by Transition Metals

Abstract Magnetic molecules known as molecular nanomagnets (MNMs; or single molecule magnets SMMs) may be the key to ultra-high density data storage. A single sub-nanometer MNM is capable of storing a single bit of information while being 2-3 orders of magnitude smaller than the magnetic domains in the current HDD technology. The best performing molecular nanomagnets are designed by carefully arranging p-element donor atoms (C, N or O) around the central magnetic ion. This strategy, however, seems to be reaching its limit as the magnetic memory effect disappears above 80 K for this class of compounds. Inspired by the structure of the hardest intermetallic magnet SmCo5, we have synthesized a nanomagnetic molecule where the central lanthanide (Ln) ion ErIII is coordinated solely by three transition metal (TM) ions in a perfectly trigonal planar fashion. The molecule [ErIII(ReICp2)3] (ErRe3) constitutes the first example of a molecular nanomagnet (MNM; or single molecule magnet SMM) with unsupported Ln-TM bonds and paves the way towards molecular intermetallics with strong direct magnetic exchange interactions. Such interactions are believed to be crucial for quenching the quantum tunneling of magnetization which limits the application of Ln-SMMs as sub-nanometer magnetic memory units.