Functional properties of the multiferroic spinel FeV₂O₄

The ferrimagnetic spinel class of materials is known for anomalous magnetoresponsive behaviors stemming from strong spin-lattice coupling and orbital ordering effects. In particular, the material FeV2O4, which has two-orbital active ions, is one of a few spinels to display type-II multiferroicity. The connection between symmetry lowering orbital-ordering transitions on the Fe/V-sites and the development of a ferroelectric polarization has yet to be understood. Furthermore, single-crystal samples demonstrate giant magnetostrictive and magnetodielectric couplings related to the behavior of magnetoelastic/multiferroic domains on the nanoscale in the bulk of the material. Here we present our ongoing work which characterizes this material on a variety of length-scales using macroscopic and scattering probes. Our results are comprised of neutron diffraction and diffuse scattering, small-angle neutron scattering, and macroscopic response measurements. By correlating these complementary datasets, we can comprehensively understand the functional properties of the material, ranging from the unit cell-level behavior to the field-response of complex domain-wall patterns observed on the mesoscale.