Magnetic Signature in Graphene Using Adsorbed Metal–Organic Networks

The interaction of a 2D metal–organic network (MON) stacked on graphene has been studied with the help of first-principles density functional theory (DFT) and DFT + U calculations. By varying the length of a polyphenyl-dicarbonitrile linker, we have evaluated the influence of the metal–metal distance on the electronic and magnetic properties of the MON complexes. Although MON composed of small molecules shows a moderately stable ferromagnetic phase, this magnetic order drops with the size of the complex. After the adsorption of MON on graphene, this last becomes n-doped due to an important charge transfer that improves with the molecular unit size. The MON–graphene interaction contributes to drastically reduce the overall stability of any magnetic order, but the local charge transfer remains strongly spin-polarized-dependent. Hence, the adsorption of magnetic MON on graphene leads to the modification of the electronic and magnetic properties of graphene, mostly in a closed proximity region to the active metal atoms of the MON. Spin-polarized scanning tunneling microscopy simulations reveal a magnetic signature in graphene that originates from its interaction with the MONs and that could be experimentally observed.