  Landau Damping (LD) mechanism of the Localized Surface Plasmon (LSP) decay is
studied for the hybrid nanoplasmonic (metal core/dielectric shell) structures.
It is shown that LD in hybrid structures is strongly affected by permittivity
and electron effective mass in the dielectric shell in accordance with previous
observations by Kreibig, and the strength of LD can be enhanced by an order of
magnitude for some combinations of permittivity and effective mass. The
physical reason for this effect is identified as electron spillover into the
dielectric where electric field is higher than in the metal and the presence of
quasi-discrete energy levels in the dielectric. The theory indicates that the
transition absorption at the interface metal-dielectric is a dominant
contribution to LD in such hybrid structures. Thus, by judicious selection of
dielectric material and its thickness one can engineer decay rates and hot
carrier production for important applications, such as photodetection and
photochemistry.
