  We examine the momentum and angular-momentum (AM) properties of monochromatic
optical fields in dispersive and inhomogeneous isotropic media, using the
Abraham- and Minkowski-type approaches, as well as the kinetic (Poynting-like)
and canonical (with separate spin and orbital degrees of freedom) pictures.
While the kinetic Abraham-Poynting momentum describes the energy flux and the
group velocity of the wave, the Minkowski-type quantities, with proper
dispersion corrections, describe the actual momentum and angular momentum
carried by the wave. The kinetic Minkowski-type momentum and AM densities agree
with phenomenological results derived by Philbin. Using the canonical
spin-orbital decomposition, previously used for free-space fields, we find the
corresponding canonical momentum, spin and orbital AM of light in a dispersive
inhomogeneous medium. These acquire a very natural form analogous to the
Brillouin energy density and are valid for arbitrary structured fields. The
general theory is applied to a non-trivial example of a surface
plasmon-polariton (SPP) wave at a metal-vacuum interface. We show that the
integral momentum of the SPP per particle corresponds to the SPP wave vector,
and hence exceeds the momentum of a photon in the vacuum. We also provide the
first accurate calculation of the transverse spin and orbital AM of the SPP.
While the intrinsic orbital AM vanishes, the transverse spin can change its
sign depending on the SPP frequency. Importantly, we present both macroscopic
and microscopic calculations, thereby proving the validity of the general
phenomenological results. The microscopic theory also predicts a transverse
magnetization in the metal (i.e., a magnetic moment for the SPP) as well as the
corresponding direct magnetization current, which explains the difference
between the Abraham and Minkowski momenta.
