The magnetic order of a manganese vanadate system with two-dimensional striped triangular lattice

Results of magnetization and neutron diffraction measurements of the manganese vanadate system Mn5(VO4)2(OH)4 are reported. The crystal structure of this compound contains triangular [Mn3O13] building blocks that produce two-dimensional Mn2+ magnetic networks with striped triangular topologies. The Mn sheets are connected through the nonmagnetic vanadate tetrahedra extending along the a-axis. Magnetization measurements performed on single crystals reveal the onset of a long-range antiferromagnetic order below approximately 45 K. The magnetic structure is Néel-type with nearest-neighbor Mn atoms coupled via three or four antiferromagnetic bonds. The magnetic moments are confined within the layers and are oriented parallel to the b direction. The magnitudes of ordered moments are reduced, presumably by geometrical frustration and the low-dimensionality of the lattice structure.