With silicon-based electronics nearing its limits, spintronics and quantum computing have emerged as technologies promising unprecedented amounts of computational power. One of the biggest challenges in these fields is engineering of systems allowing full control over large arrays of identical spin-centres. In this project I aim to tackle this issue by fabricating a spintronic device in which one of the crucial parameters - the magnetic coupling between individual spin centres - can be efficiently modulated. This will be achieved by synthesizing a magnetic metal-organic network on top of a graphene fieldeffect transistor. Here, the metal-organic network allows precise positioning of magnetic atoms into long-range-ordered lattices, and the gated graphene substrate enables precise tuning of the charge transfer from the deposited molecules via the applied gate voltage. Thus, this project simultaneously addresses practical issues in device fabrication, as well as the fundamental mechanisms of magnetic coupling.