Maxim Mostovoy, University of Groningen
Spontaneous breaking of inversion symmetry by a spin ordering couples magnetism to ferroelectricity and gives rise to spectacular effects such as the rotation of electric polarization by magnetic field and giant magnetocapacitance observed in rare earth manganites. The coupling between magnetic and electric response is often found in frustrated magnets with unconventional magnetic orders. I will show that the 120^o -spin ordering on a Kagome lattice can give rise to a linear magnetoelectric effect. Furthermore, the dynamic coupling between spin and polarization waves makes possible to observe single-magnon excitations in optical absorption experiments (the so-called electromagnon peaks). I will discuss microscopic mechanisms of the static and dynamic magnetoelectric coupling and show how optical studies of rare earth manganites can give us information about competing ferroelectric states in these materials.