  Material losses in metals are a central bottleneck in plasmonics for many
applications. Here we propose and theoretically demonstrate that metal losses
can be successfully mitigated with dielectric particles on metallic films,
giving rise to hybrid dielectric--metal resonances. In the far field, they
yield strong and efficient scattering, beyond even the theoretical limits of
all-metal and all-dielectric structures. In the near field, they offer
high-Purcell-factor (${>}5000$), high-quantum-efficiency (${>}90\%$), and
highly directional emission at visible and infrared wavelengths. Their quality
factors can be readily tailored from plasmonic-like (${\sim}10$) to
dielectric-like (${\sim}10^3$), with wide control over the individual resonant
coupling to photon, plasmon, and dissipative channels. Compared with
conventional plasmonic nanostructures, such resonances show robustness against
detrimental nonlocal effects and provide higher field enhancement at extreme
nanoscopic sizes and spacings. These hybrid resonances equip plasmonics with
high efficiency, which has been the predominant goal since the field's
inception.
