On the Effect of Dissipation and Nonlocality on Unidirectional and Topological Surface Plasmon-Polaritons

Unidirectional surface plasmon polaritons (SPPs) on nonreciprocal material platforms are currently the subject of significant interest. In this abstract, we revisit this exciting topic, discussing the role of the nonlocal response of a magnetized plasmonic material. Our analytical calculations and frequency-domain finite-element simulations confirm that a nonlocal correction in the material model implies the absence of purely unidirectional SPP modes below the plasma frequency. However, we also show that, depending on the considered configuration, the presence of even moderate levels of loss (absorption or radiation) can practically restore the unidirectionality of this mode. Our findings have important implications in the context of nonreciprocal and topological electromagnetic systems.