Spectrum of Coupled Waves in Orthorhombic Multiferroics With Cycloidal Antiferromagnetic Structure in External Electric and Magnetic Fields

Spectrum of coupled spin, acoustic, electro-dipole and electromagnetic waves in orthorhombic perovskite multiferroics placed in external electric and magnetic field has been calculated. Frequency and field dependencies of electric, magnetic, and magnetoelectric susceptibilities of multiferroics with cycloidal antiferromagnetic structure in external electric and magnetic fields have been investigated as well. The spectrum of coupled waves has a band structure. Width and frequency ranges of bands depend on external fields. The possibility of control of electrodynamic properties of orthorhombic perovskite multiferroics with cycloidal antiferromagnetic structure by external electric and magnetic fields has been shown.