Electric field control of multiferroic domains in Ni₃ V ₂ O₈ imaged by x-ray polarization-enhanced topography

The magnetic structure of multiferroic Ni₃ V₂ O ₈ has been investigated using nonresonant x-ray magnetic scattering. Incident circularly polarized x rays combined with full polarization analysis of the scattered beam is shown to yield high sensitivity to the components of the cycloidal magnetic order, including their relative phases. Information on the magnetic structure in the ferroelectric phase is obtained, where it is found that the magnetic moments on the "cross-tie" sites remain disordered. This implies that the onset of ferroelectricity is associated mainly with spine site magnetic order. We also demonstrate that our technique enables the imaging of multiferroic domains through polarization enhanced topography. This approach is used to image the domains as the sample is cycled by an electric field through its hysteresis loop, revealing the gradual switching of domains without nucleation.