Symmetry of multiferroicity in a frustrated magnet TbMn2O5

Abstract

Based on measurements of soft-x-ray magnetic scattering and symmetry considerations, we demonstrate that the magnetoelectric effect in TbMn2O5 arises from an internal field determined by (S) over right arrow ((q) over right arrow) x (s) over right arrow (-(q) over right arrow) with (S) over right arrow ((q) over right arrow) being the magnetization at modulation vector (q) over right arrow, whereas the magnetoelastic effect in the exchange energy governs the response to external electric fields. Our results set fundamental symmetry constraints on the microscopic mechanism of multiferroicity in frustrated magnets.