Low-magnetic-field control of electric polarization in a conical helimagnet Ba_2Mg_2Fe_(12)O_(22)

摘要

The discovery of a gigantic magnetoelectric (ME) effect in TbMnO_3 and the subsequent studies have established the fact that a spiral spin order and the accompanied lattice distortion cause symmetry breaking and produce a ferroelectric polarization. Although a great number of works have been devoted to this class of multiferroics characterized by a spiral spin order, the limitation of the temperature or field ranges of the available data hampers their uptake towards possible applications. According to the spin-current model, or the inverse Dzyaloshinski-Moriya model, cycloidal and transverse conical helimagnets, the screw axis of which is perpendicular to the propagation vector, are allowed to have a ferroelectric polarization.