Influence of electric fields on spin waves in simple ferromagnets: Role of the flexoelectric interaction

We discuss the influence of electric fields on spin waves in simple ferromagnets produced by the flexoelectric interaction. Such terms produce a frequency shift that is linear in both the applied electric field and the wave vector of the spin waves. Above a certain critical electrical field, ferromagnetism is unstable. We discuss the nature of the conical cycloidal state that appears above the critical field for a ferromagnet with uniaxial anisotropy and exchange.