Electronic Structure of a Mn6 Single Molecule Magnet (S=4) grafted on Au(111)

Single molecule magnets (SMMs) form a new class of magnetic materials consisting of identical nanoscaleparticles that can show magnetization in the absence of a magnetic field. We have experimentally and theoreticallyinvestigated the low-spin (S=4) member of the Mn6 SMM family, properly functionalized with two3-thiophenecarboxylate (3tpc) ligands in order to graft it on to a Au(111)surface. We report the theoreticaldensity of states calculated within the local density approximation (LDA) scheme accounting for the on-siteCoulomb repulsion (LDA+U) for U values ranging from 0 to 8 eV. On the experimental side, by exploitingresonant photoemission at the Mn 2p edge, we were able to single out the Mn 3d derived states in the valenceband energy region for a submonolayer distribution of Mn6-3tpc deposited on Au(111). From the comparisonbetween the experimentally derived 3d density of states and the theoretical one, we found that the bestagreement occurs for a U value of 4 eV. From the binding energy of Mn 2p3/2 core line, measured in situ, wealso derived a value for the 2p-3d correlation energy of about 5 eV—in agreement with previousdetermination.