Nonreciprocal light diffraction by a lattice of magnetic vortices

We report an experimental study of the optical properties of a two-dimensional square lattice of triangle Co and CoFe nanoparticles with a vortex magnetization distribution. We demonstrate that the intensity of light scattered in the diffraction maxima depends on the vorticity of the particles' magnetization and can be manipulated by applying an external magnetic field. The experimental results can be understood in terms of simple phenomenological consideration.