Topological insulators (TIs) are one of the most important recent discoveries in condensed matter physics. Their dissipationless conduction and large spin-orbit coupling make TIs particularly suited for new spin and spin-orbit devices.Control of the surface state is essential if these materials are to be used for new devices.We are interested in producing TI based heterostructures of different materials to enable a high degree of control and tunability of the TI interface. Here we intend tailor the properties of doped TIs through fabrication of superlattices based on layers with different FM dopants. In particular we intend to study if proximity to a Dy-doped interface can suppress low temperature magnetic fluctuations in weakly doped Cr-doped layers. Weakly doped Cr layers exhibit the Quantum Anomalous Hall effect at very low temperatures despite having a TC orders of magnitude higher.