Electromagnetic Waves in Canted Magnets

The optical properties of canted antiferromagnets are discussed from the perspective of magnetic polaritons and field tunable electromagnetic (EM) properties. Canted antiferromagnets have a weak magnetization. Their EM properties can be affected by externally applied magnetic fields as well as electric fields, if the material is multiferroic. A theoretical approach that is useful for describing the THz frequency EM response and properties of a large variety of canted spin systems is outlined here. The properties of two example systems are discussed: an antiferromagnet in which spin canting is induced through an externally applied magnetic field; and an antiferromagnetic multiferroic wherein the magnetic sublattices are canted through an internal coupling to a spontaneous dielectric polarization.