Dispersion properties of nonlinear bulk polaritons in uniaxial antiferromagnetic/nonmagnetic superlattices

Abstract We present the expressions of nonlinear effective susceptibilities of antiferromagnetic/nonmagnetic superlattices with an effective-medium method, and then on this basis investigate nonlinear dispersion properties of antiferromagnetic polaritons in the superlattices. In the geometry used in the paper, the y-axis is normal to the interface, and the z-axis is pointed along the anisotropy axis. The theoretical analysis and numerical calculations show: (i) The nonlinearity has no contributions to the waves traveling along the three axes, and to the waves in the x–y plane. (ii) The nonlinear shift in wave number is either upward or downward, depending on the mode frequency larger or less than the resonance frequency, for the wave traveling along the other directions.