the bulk bands for an inverse of the phonon mass of 0.015 f is shown in Fig. 6(a)  where the magnetic resonance is lower than the dielectric resonance. The effects of a magnetic resonance above the dielectric resonance  with 0.009 f  are shown in Fig. 6(b). Only band overlap and intersections are affected. Note a consequence of this for the surface modes. In the case where the magnetic resonance is below the dielectric resonance  have a broader range in wavevector (see Fig. 6(a)) compared to the case where the magnetic resonance is above the dielectric resonance (in Fig. 6(b)). Dispersion relations for a material having linear magnetoelectric coupling have been cal- culated for tranverse electric polariton modes. Effects associated with spin canting are considered. The polarisation and weak ferromagnetism are parallel to the surface  and the antiferromagnet magnetisations are out of plane. We find surface modes associated with the weak ferromagnetism that are non-reciprocal with respect to propagation direction  such that ω ( ⃗ k ) = ω ( − ⃗ k ). For sufficiently large magnetic fields  or different material parameters  surface modes may also exist in the magnetostatic region  with k ≫ ω/c . Application of static magnetic field can be used to modify the middle bulk band frequencies We wish to acknowledge the support of Ausaid  the Australian Research Council and DEST. ACKNOWLEDGMENTS V. CONCLUSIONS 15 [1] R. E. Camley and D. L. Mills  Phys. Rev. 26   1280 (1982). [2] K. Welford  Opt Quant. Elec. 23   1 (1991). [3] G. Cairns  D. McNeill  and P. Dawson  Surf. Sci. 429   117 (1999). [4] F. KeilMann  J. Micros. 194   567 (1999). [5] V. N. Konopsky and E. V. Alieva  Phys. Rev. Let 97   253904 (2006). [6] R. W. Damon and J. R. Esbach  J. Phys. Chem. Solids. 19   308 (1961).