Controlling the Magnetic Properties of a Single Phthalocyanine Molecule through its Strong Coupling with the GaAs Surface

Results of an ab initio DFT (density functional theory) investigation of the paramagnetic vanadyl-phthalocyanine (VOPc) adsorbed on the GaAs (001) surface indicate that a Pc molecule equipped with a central metal-nonmetal pair gives rise to a strong molecule-semiconductor coupling that directly involves the central transition metal (TM) and permits to manipulate its magnetic properties. The nonmetal atom plays a key role in achieving such a remarkable effect by binding the molecule to the surface, permitting a substrate-to-molecule charge-transfer, and inducing a robust TM high spin configuration. The present model of organic-inorganic coupling can have a particular value because it involves semiconductor substrates, which generally give rise to a weak coupling with Pc molecules. It also indicates an alternative route for controlling the molecular magnetic properties, thus offering further degrees of freedom and opening wider perspectives for realizing single-molecule-based spintronics devices.