Exchange‐Coupled Two‐Dimensional MOFs

ABSTRACT 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.