Cu3Nb2O8: A Multiferroic with Chiral Coupling to the Crystal Structure
ORAL
Abstract
We will present recent bulk properties, neutron powder diffraction, and non-resonant x-ray diffraction measurements on a new multiferroic material, Cu$_3$Nb$_2$O$_8$. We demonstrate than an electric polarization evolves simultaneously with a generalised helicoidal magnetic ordering. Contrary to conventional models of multiferroicity, the electric polarization was found to lie perpendicular to the common rotation plane of the magnetic moments. We present a new model applicable to a specific class of crystals; those that support a macroscopic``ferroaxial'' vector and adopt a helicoidal magnetic structure. Our new interpretation, which may explain the multiferroic properties of a number of systems reported in recent literature, is based upon the well-understood inverse Dzyaloshinskii-Moriya interaction, but requires an altogether different interpretation.
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