The Casimir force between dissimilar mirrors and the role of the surface   plasmons
  We investigate the Casimir force between two dissimilar plane mirrors the material properties of which are described by Drude or Lorentz models. We calculate analytically the short and long distance asymptote of the force and relate its behavior to the influence of interacting surface plasmons. In particular we discuss conditions under which Casimir repulsion could be achieved. 
A. Lambrecht and I. G. Pirozhenko