  Spin-orbit (SO) coupling can be introduced in a Bose--Einstein condensate
(BEC) as a gauge potential acting only in a localized spatial domain. Effect of
such a SO "defect" can be understood by transforming the system to the
integrable vector model. The properties of the SO-BEC change drastically if the
SO defect is accompanied by the Zeeman splitting. In such a non-integrable
system, the SO defect qualitatively changes the character of soliton
interactions and allows for formation of stable nearly scalar soliton complexes
with almost all atoms concentrated in only one dark state. These solitons exist
only if the number of particles exceeds a threshold value. We also report on
the possibility of transmission and reflection of a soliton upon its scattering
on the SO defect. Scattering strongly affects the pseudo-spin polarization and
can induce pseudo-spin precession. The scattering can also result in almost
complete atomic transfer between the dark states.
