Topology and exceptional points of massive Dirac models with generic non-Hermitian perturbations

Recently, there has been a lot of activity in the research field of topological non-Hermitian physics, driven by both fundamental interest and potential applications. Here, the authors systematically investigate and classify Dirac-type systems with non-Hermitian perturbations. They find that there are three different types of non-Hermitian terms. For each case, they determine the bulk exceptional points, the boundary modes, and the band topology. These findings serve as guiding principles for the design of applications, for example, in photonic lattices.