# Surface and bulk TM polaritons in a linear magnetoelectric multiferroic with canted spins 

School of Physics M013, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia 

V. Gunawan ∗ and R.L. Stamps 

(Dated: September 17, 2018) 

## Abstract 

We present a theory for surface polaritons on ferroelectric-antiferromagnetic materials with canted spin structure. Canting is assumed to be due to a Dzyaloshinkii-Moriya interaction with the electric polarisation and weak ferromagnetism directed in the plane parallel to the surface. Surface and bulk modes for a semi-infinite film are calculated for the case of transverse magnetic polarisation. Example results are presented using parameters appropriate for BaMnF$_{4}$. We find that the magnetoelectric interaction gives rise to ”leaky” surface modes, i.e. pseudosurface waves that exist in the pass band, and that dissipate energy into the bulk of material. We show that these psuedosurface mode frequencies and properties can be modified by temperature, and application of external electric or magnetic fields. 

PACS numbers: 71.36+c;78.20.Jq;78.20.Ls 

