A switchable molecular device is constructed by contacting an individual nanoparticle based on spin‐crossover molecules between nanometer‐spaced electrodes. The switching and memory effects near room temperature are a consequence of the intrinsic bistability of the nanoparticle. Interestingly, for molecular spintronics, the spin crossover can also be induced by applying a voltage, showing that its magnetic state is electrically controllable.

We have measured quantum transport through an individual Fe(4) single-molecule magnet embedded in a three-terminal device geometry. The characteristic zero-field splittings of adjacent charge states and their magnetic field evolution are observed in inelastic tunneling spectroscopy. We demonstrate that the molecule retains its magnetic properties and, moreover, that the magnetic anisotropy is significantly enhanced by reversible electron addition/subtraction controlled with the gate voltage. Single-molecule magnetism can thus be electrically controlled.

Low-temperature three-terminal transport measurements through a thiol end-capped pi-conjugated molecule have been carried out. Electronic excitations, including zero and finite-bias Kondo-effects, have been observed and studied as a function of magnetic field. Using a simplified two-orbital model, we have accounted for the spin and the electronic configuration of the first four charge states of the molecule. The charge-dependent couplings to gate, source, and drain electrodes suggest a scenario in which charges and spins are localized at the ends of the molecule, close to the electrodes.