  Light carries both spin and momentum. Spin-orbit interactions of light come
into play at the subwavelength scale of nano-optics and nano-photonics, where
they determine the behaviour of light. These phenomena, in which the spin
affects and controls the spatial degrees of freedom of light, are attracting
rapidly growing interest. Here we present results on the spin-momentum locking
in the near field of metal nanostructures supporting localized surface
resonances. These systems can confine light to very small dimensions below the
diffraction limit, leading to a striking near-field enhancement. In contrast to
the propagating evanescent waves of surface plasmon-polariton modes, the
electromagnetic near-field of localized surface resonances does not exhibit a
definite position-independent momentum or polarization. Our results can be
useful to investigate the spin-orbit interactions of light for complex
evanescent fields. Note that the spin of the incident light can control the
rotation direction of the canonical momentum.
