  We investigate the Casimir stress on a topological insulator (TI) between two
metallic plates. The TI is assumed to be joined to one of the plates and its
surface in front of the other is covered by a thin magnetic layer, which turns
the TI into a full insulator. We also analyze the limit where one of the plates
is sent to infinity yielding the Casimir stress between a conducting plate and
a TI. To this end we employ a local approach in terms of the stress-energy
tensor of the system, its vacuum expectation value being subsequently evaluated
in terms of the appropriate Green's function. Finally, the construction of the
renormalised vacuum stress-energy tensor in the region between the plates
yields the Casimir stress. Numerical results are also presented.
