Probing Superexchange Interaction in Molecular Magnets by Spin-Flip Spectroscopy and Microscopy

The superexchange mechanism in cobalt phthalocyanine (CoPc) thin films was studied by a low temperature scanning tunneling microscope. The CoPc molecules were found to form one-dimensional antiferromagnetic chains in the film. Collective spin excitations in individual molecular chains were measured with spin-flip associated inelastic electron tunneling spectroscopy. By spatially mapping the spin-flipping channels with submolecular precision, we are able to explicitly identify the specific molecular orbitals that mediate the superexchange interaction between molecules.