Conference Paper

Chern insulators have attracted significant interest in recent years due to their ability to support backscattering-immune guided wave propagation. Photonic Chern insulators, which can be realized in photonic crystals or in electromagnetic continua, are characterized by topological invariants known as gap Chern numbers. In this work, we explore nonreciprocal electromagnetic continua that exhibit large gap Chern numbers, beyond the typical value of ±1. We demonstrate that these topological phases can emerge naturally as a result of competing nonlocal effects. To illustrate this phenomenon, we analyze a two-carrier plasma subjected to a static magnetic field. To accurately model the interaction between the carriers and the electromagnetic field, we consider two distinct nonlocal mechanisms. Using a first-principles approach, we numerically compute these topological invariants and establish a connection between the different topological phases and the Weyl points supported by the material in three-dimensional momentum space. Our work contributes to a deeper understanding of the physical mechanisms that can underpin topological phases with large topological invariants.