Superscattering of Light from Core-Shell Nonlocal Plasmonic Nanoparticles

We study the scattering properties of coated nanoparticles with high-permittivity core and nonlocal plasmonic shell with full-wave nonlocal Mie theory. Both electric and artificial magnetic resonances of different orders are supported simultaneously for such coated particles. By properly engineering the aspect ratio, we can achieve not only the overlapping of electric dipole (ED) and magnetic dipole (MD) modes but also that of electric quadrupole (EQ) and magnetic quadrupole (MQ). We numerically demonstrate that there are two overlapping ways to obtain the superscattering state for core-shell nanoparticles. Furthermore, we show that the nonlocality becomes less important in the scattering of coated nanoparticles with ultrathin shell thickness but large total size due to the fact that nonlocality is essentially a surface effect.