Nuclear and magnetic structure of Ca2MnWO6: A neutron powder diffraction study

The nuclear and magnetic structures of the double provskite compound Ca2MnW O6 have been determined by neutron powder diffraction. Rietveld refinement shows that the compound adopts a monoclinic crystal structure with P2(1)/n symmetry. Magnetic refinement at 10 K shows that the magnetic structure is based on a unit cell related to that of the nuclear structure by a propagat ion vector (0 1/2 1/2), which is not very common in the case of double pero vskites. The crystal contains alternating MnO6 and WO6 octahedra, considera bly tilted due to the relative small size of the cation that occupy the A-s ublattice of the perovskite. The manganese magnetic moments are coupled ant iferromagnetically along the unit cell axes with the magnetic moment equal to 3.49(2) mu (B) (M-x = 1.08(13) mu (B), M-y = 0.94(7) mu (B), M-z = 3.20( 4) mu (B)). Antiferromagnetic behavior was confirmed by magnetization measu rements, and the antiferromagnetic to paramagnetic transition was found at 16 +/- 0.1 K. (C) 2001 Elsevier Science Ltd. All rights reserved.