  We present an electrodynamical model of a novel quantum plasmonic device -
magneto-optical spaser. It is shown that a spherical gain nanoparticle coated
with a metallic magneto-optical shell can operate as a spaser amplifying
circularly polarized surface plasmons. The magneto-optical spaser may be used
in design of optical isolator in plasmonic transmission lines as well as in
spaser spectrometry of chiral molecules.
