Fermi arcs, drumhead states and nodal planes in CoS₂

Since the discovery of the first topological material 15 years ago, the search for material realizations of novel topological phases has become the driving force of the field. While oftentimes we search for new materials, we forget that well established materials can also display very interesting topological properties. In this work, we revisit CoS₂, a metallic ferromagnetic pyrite that has been extensively studied in the literature due to its magnetic properties. We study the topological features of its electronic band structure and identify protected crossings, a 4-fold Fermion, Weyl nodes, Nodal lines and Nodal planes. Looking at different surface terminations, we find Fermi arcs stemming from Weyl node projections and drumhead states from Nodal line projections.