Surface and bulk polaritons in a PML-type magnetoelectric multiferroic with canted spins:TE and TM polarization

Abstract

We present a theory for surface polaritons on ferroelectric–antiferromagnetic materials withcanted spin structure. A small uniform canted moment is allowed, resulting in a weakferromagnetism directed in the plane parallel to the surface. Surface and bulk polariton modesfor a semi-infinite film are calculated for the case of transverse electric (TE) and transversemagnetic (TM) polarization. Example results are presented using parameters appropriate forBaMnF4. We find that the surface modes are non-reciprocal for the TE polarization due to themagnetoelectric interaction, and the non-reciprocity can be controlled by an appliedelectric field. Example results for attenuated total reflection (ATR) are calculated. Themagnetoelectric interaction also gives rise to ‘leaky’ surface modes in the case of TMpolarization. These are pseudo-surface waves that exist in the pass band, and dissipateenergy into the bulk of the material. We show that these pseudo-surface mode frequenciesand properties can be modified by temperature and the application of external electric ormagnetic fields.