Nonlocal Hydrodynamic Response of Plasmonic Structures at Deep-nanometer Scale

The electromagnetic properties of plasmonic nano-antennas and scatterers with the characteristic dimensions at deep-nanometer scale, governed by quantum mechanical effects, have been extensively studied by a hydrodynamic approach. Several hydrodynamic models, together with additional boundary conditions, have been proposed to deal with the collective motion of the free electron gas in metals. In this work, four hydrodynamic models, namely the hard-wall hydrodynamic model, the curl-free hydrodynamic model, the shear forces hydrodynamic model, and the quantum hydrodynamic model are employed. The study is performed for a deep-nanometer metal core–dielectric shell sphere, excited by a plane wave. It is demonstrated that the far field characteristics of the core–shell nanosphere are largely affected by the choice of a specific hydrodynamic model.