Chemically functionalized magnetic exchange interactions of hybrid organic-ferromagnetic metal interfaces

We theoretically explore through systematic multiscale ab initio and Monte Carlo calculations how the surface magnetism of a ferromagnetic surface can be fine-tuned by nonmagnetic organic molecules containing a single π bond. We demonstrate that a magnetic hardening or softening can be induced depending on the electronegativity of the heteroatom or when the π-bond ``bridges'' the magnetic surface atoms. Finally, the Monte Carlo simulations revealed taylored macroscopic hysteresis loops corresponding to soft and hard molecule-surface magnets.