Exchange‐Coupled Two‐Dimensional MOFs

In two-dimensional metal-organic frameworks (2D MOFs), the orientation of the magnetic response is generally assumed to be set by local coordination and lattice symmetry. Here we show that, in an extended two-dimensional coordination network, a remanent molecular magnetic response can instead be imposed by the underlying ferromagnetic substrate. Using element-specific X-ray magnetic circular dichroism, we investigate Fe- and Ni-tetracyanobenzene (TCNB) networks on graphene/Co and demonstrate graphene-mediated ferromagnetic coupling between the molecular layer and the cobalt film. Unlike previous studies on isolated molecules and dense molecular layers, this work extends substrate-mediated interface magnetism to an electronically connected metal-organic framework. By tuning the cobalt thickness across its spin-reorientation transition, we control the orientation of the remanent Fe-TCNB response, which changes from predominantly out-of-plane to in-plane without altering the framework chemistry or structure. Whereas Ni-TCNB shows a field-polarized but non-remanent response, Fe-TCNB exhibits a remanent substrate-coupled component that persists up to room temperature. These results establish substrate engineering as a route to stabilizing and orienting molecular magnetization in two-dimensional metal-organic frameworks.