Self-Assembly and Superexchange Coupling of Magnetic Molecules on Oxygen-Reconstructed Ferromagnetic Thin Film

We report on the distinctive molecular assembly and exchange coupling of paramagnetic manganese(III) teraphenylporphyrin chloride (MnTPPCl) molecules on a metallic cobalt (Co(001)) and on an oxygen-reconstructed cobalt (O/Co(001)) substrate, the latter substrate being prepared by surfactant-mediated growth. For MnTPPCl, a ferromagnetic (FM) exchange coupling to Co(001) and an antiferromagnetic (AFM) exchange coupling to O/Co(001) were identified. The random adsorption of MnTPPCl on Co(001) is turned into a self-assembled and well-ordered 2D molecular domains on O/Co(001). Different oxidation states for Mn ions are found to exist on different substrates. The here presented spectro-microscopy-correlation approach, involving X-ray magnetic circular dichroism (XMCD) spectroscopy, X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), and scanning tunneling microscopy (STM), demonstrates its strength to identifty the mechanism involved in organic spintronic interfaces.