We report transport measurements through a single-molecule magnet, the ${\mathrm{Mn}}_{12}$ derivative $[{\mathrm{Mn}}_{12}{\mathrm{O}}_{12}({\mathrm{O}}_2\mathrm{C}\mathrm{\text{−}}{\mathrm{C}}_6{\mathrm{H}}_4\mathrm{\text{−}}\mathrm{SAc}{)}_{16}({\mathrm{H}}_2\mathrm{O}{)}_4]$, in a single-molecule transistor geometry. Thiol groups connect the molecule to gold electrodes that are fabricated by electromigration. Striking observations are regions of complete current suppression and excitations of negative differential conductance on the energy scale of the anisotropy barrier of the molecule. Transport calculations, taking into account the high-spin ground state and magnetic excitations of the molecule, reveal a blocking mechanism of the current involving nondegenerate spin multiplets.

Polynuclear compounds of magnetic transition metal ions are attracting large interest after the discovery that their magnetisation may relax very slowly at low temperature. Since their behaviour is similar to that of bulk magnets they may be called single molecule magnets. Here we review the magnetic properties of iron(III) clusters showing such features which may be interesting for future applications, as well as strategies for designing new molecules with increased performances.

Addressing individual bistable magnetic molecules, known as Single Molecule Magnets (SMMs), is a fascinating goal at the borderline between molecular magnetism and spin electronics. This tutorial review focuses on the first step towards single-molecule experiments, namely the organization of SMMs on surfaces. Both preparation and characterization of surface-supported SMMs prove to be quite demanding and a multidisciplinary approach is necessary, which is described here using selected examples. We first illustrate the chemical strategies devised to assemble SMMs and to control their orientation on surfaces. Then, we present characterization tools, which have been selected on the basis of their relevance to address specific points, i.e. the chemical composition of the deposited SMM films, the organization of the molecules on the surface, the intramolecular arrangement of the spins, the magnetic anisotropy of SMMs, and eventually the dynamics of their magnetization on surfaces. Particular attention is devoted to techniques exploiting synchrotron light.