The idea that a molecule could act as a magnet that manifests previously unobserved quantum behavior can be traced to theoretical predictions of a magnetic analogue to quantum mechanical tunneling of a particle through a potential energy barrier. The magnetic version would involve tunneling through an energy barrier that hinders reorientation of the magnet’s north and south poles. Observation of the effect would require measurements on nanoscale objects that are much smaller than any that could be fabricated via the top-down methods—involving shrinking larger objects—that were available at the time that the idea first emerged.
An important breakthrough came from studies of molecular metal oxide clusters created via bottom-up, atom-by-atom chemical synthesis. The molecules were designed to mimic protein reaction centers, which play important roles in various biological processes, including photosynthesis. They would lead to the first demonstration of magnetic bistability—in which a magnetic dipole can be switched between the...
