  We report the prediction of a new type of Dyakonov surface waves that
propagate along the flat strip of the interface between two dielectrics with
negative anisotropy. It is shown that the surface waves condition is satisfied
for negatively anisotropic dielectrics due to specific boundaries of the strip
waveguide confined between two metallic plates. Such modes are studied by the
perturbation theory in the approximation of weak anisotropy. The existence of
Dyakonov surface waves in negative uniaxial crystals motivates us to reconsider
the list of materials suitable for their practical implementation. We believe
that this work opens a new unexplored research area in the field of surface
waves.
