  Photoelectric properties of metamaterials containing non-centrosymmetric,
similarly oriented metallic nanoparticles embedded in a homogeneous
semiconductor matrix are theoretically studied. Due to the asymmetric shape of
the nanoparticle boundary, photoelectron emission acquires a preferred
direction, resulting in a photocurrent flow in that direction when
nanoparticles are uniformly illuminated by a homogeneous plane wave. This
effect is a direct analogy of the photogalvanic (or bulk photovoltaic) effect
known to exist in media with non-centrosymmetric crystal structure, such as
doped lithium niobate or bismuth ferrite, but is several orders of magnitude
stronger. Termed the giant plasmonic photogalvanic effect, the reported
phenomenon is valuable for characterizing photoemission and photoconductive
properties of plasmonic nanostructures, and can find many uses for
photodetection and photovoltaic applications.
