  We investigate theoretically the effect of an external magnetic field on
polarization patterns appearing in quantum microcavities due to the optical
spin Hall effect (OSHE). We show that increase of the magnetic field
perpendicular to the plane of the cavity resulting in the increase of the
Zeeman splitting leads to the transition from azimuthal separation of
polarizations to their radial separation. This effect can be straightforwardly
detected experimentally.
