Neutron diffraction study of monoclinic brannerite-type CoV2O6

A variable-temperature powder neutron diffraction study of the monoclinic brannerite-type CoV2O6 (space group C2/m, a=9.2531(2), b=3.5040(1), c=6.6201(1)  Å and β=111.617(1)° at 300 K) is reported. No structural transition is observed down to 4 K, but a magnetostriction accompanying antiferromagnetic order at TN=15 K is discovered. Antiferromagnetic order observed below TN has an a×b×2c supercell in which Co2+ moments of magnitude 4.77(4) μB at 4 K lie in the ac plane and are ferromagnetically coupled within chains of edge-sharing CoO6 octahedra parallel to b. Ferromagnetic chains are coupled antiferromagnetically to neighbouring chains in the a and c directions, and a model for the interchain order in the reported 1/3 magnetization plateau region is proposed.

Antiferromagnetic order of Co2+ moments in monoclinic brannerite type CoV2O6 results in a magnetostriction at the 15 K Neel transition. An alternative coupling between ferromagnetic chains is proposed to account for a 1/3 magnetization plateau in this material.Figure optionsDownload as PowerPoint slideHighlights
► Variable-temperature powder neutron diffraction study of the monoclinic brannerite-type CoV2O6 is reported.
► Magnetostriction accompanying antiferromagnetic order at TN=15 K in monoclinic CoV2O6 is discovered.
► Antiferromagnetic order in a×b×2c supercell of CoV2O6 is determined.
► Model for spin order in the reported 1/3 magnetization plateau of CoV2O6 is proposed.