Dyakonov surface polaritons in antiferromagnet film

Abstract

Abstract Dyakonov surface polaritons (DSPs) in a single antiferromagnetic (AF) film are investigated in the parallel geometry where the AF anisotropic axis is parallel to the film and no external magnetic field is applied. The analytical dispersion relation is obtained and four surface modes are found, among which one symmetric mode and an anti-symmetric mode are exist in the AF reststrahlen frequency band, and another symmetric and anti-symmetric modes are situated out the reststrahlen band. The existence of symmetric and anti-symmetric modes is caused by the mirror symmetry and finite thickness of the AF film. A pair of modes in the band have magnetostatic limits but the other pair out the band do not. The dispersion properties, field and energy-flux density distributions of each DSP are numerically calculated based on the FeF2 film for various propagating directions and film thicknesses. It is very interesting that the energy flux of each DSP can seriously deviates from its propagation direction, and the largest walk-off angle can reach 200°. In addition, we briefly discuss dispersion properties of Dyakonov odd and even guided modes, they also are symmetric and antisymmetric and have multiple solutions.