Powder neutron diffraction analysis and magnetic structure of kagomé-type vanadium jarosite NaV3(OD)6(SO4)2

Neutron and x-ray diffraction experiments were performed on pure, deuterated samples of the vanadium jarosite compound, ${\mathrm{NaV}}_{3}(\mathrm{OD}{)}_{6}({\mathrm{SO}}_{4}{)}_{2},$ to investigate its structure and magnetism. The crystal structure was refined using combined single-crystal x-ray and powder neutron diffraction methods. To determine the magnetic structure, neutron powder diffraction measurements were performed at 217 and 16 K. Analysis of the data reveals that the unpaired spins located on the ${\mathrm{V}}^{3+}$ ions couple ferromagnetically within the ${\mathrm{V}}_{3}(\mathrm{OD}{)}_{6}({\mathrm{SO}}_{4}{)}_{2}^{\ensuremath{-}}$ triangles of the Kagom\'e layers with the spins oriented parallel to the layers. Spins in adjacent layers order antiferromagnetically. The temperature dependence of magnetic diffraction peak intensities yields a zero-field critical transition temperature of ${T}_{c}=34.3(5)\mathrm{K}.$ The intralayer ferromagnetic interaction propagates along the Kagom\'e lattice via the \ensuremath{\pi}-symmetry orbitals of a -$[{\mathrm{V}}^{3+}\ensuremath{-}\mathrm{OD}\ensuremath{-}{\mathrm{V}}^{3+}]$- pathway.