Our work focuses on the growth of Heusler compounds by molecular beam epitaxy and characterization of their atomic, electronic, topological, and magnetic properties. These properties can be tuned chemically via the number of valence electrons. Examples include the half-metals Co2MnSi and Co2MnAl, the semiconductors NiTiSn and CoTiSb, the topologically non-trivial PtLuSb and PtLuBi, and Weyl semi-metal candidate Co2TiGe.