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

The nuclear and magnetic structures of the double provskite compound Ca2MnWO6 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 propagation vector (0 1/2 1/2), which is not very common in the case of double perovskites. The crystal contains alternating MnO6 and WO6 octahedra, considerably tilted due to the relative small size of the cation that occupy the A-sublattice of the perovskite. The manganese magnetic moments are coupled antiferromagnetically 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 measurements, and the antiferromagnetic to paramagnetic transition was found at 16 +/- 0.1 K. (C) 2001 Elsevier Science Ltd. All rights reserved.