Hybrid exceptional point created from type-III Dirac point

Abstract

Degeneracy points and exceptional points embedded in the energy band are distinct because of their topological features. We report a hybrid exceptional point formed through merging two ordinary exceptional points with opposite chiralities that were created from the type-III Dirac points emerging from a flat band. The hybrid exceptional point is induced by the destructive interference at the proper match between the non-Hermiticity and the synthetic magnetic flux. The degeneracy points and different types of exceptional points are distinguishable by their topological features of the global geometric phase accompanied by the scaling exponent of phase rigidity. Our findings not only pave the way for creating, moving, and merging exceptional points but also shed light on future investigations of non-Hermitian topological phases.