Electronic structure of a metallic ferromagnetic pyrite

In this work we present combined experimental and theoretical results to elucidate electronic and magnetic properties of metallic cobalt pyrite CoS₂. On one side we reveal that the Density Functional Theory predicted band structure is in good agreement with angular resolved photoemission spectroscopy (ARPES) measurements, performed for the first time. Further studying its band structure we discovered that this material exhibits topological behaviour. Close to the Fermi level, we found a potential 'New Fermion', a 4-dimensional magnetic band crossing protected by cubic, non-symmorphic magnetic symmetries, along with several neighbouring Weyl fermions. We finally analyze the surface states and identify surface Fermi arcs.