Neutron diffraction study of the layered compounds MnPSe3 and FePSe3

In the insulating compounds MnPSe3 (1) and FePSe3 (2) the divalent transition metal ions form planar honeycomb lattices. A neutron diffraction study revealed a collinear antiferromagnetic order below TN = 74 ± 2 K (1) and TN = 119 ± 1 K (2) with the corresponding wavevectors k = [000] (1) and k = [12 0 12] (2). In MnPSe3 the magnetic moments (m0 = 4.74 μB) lie within the basal plane and in FePSe3 (m0 = 4.9 μB) they are pointing along the c-axis. The collinear structures are determined by the dominating intralayer interactions between first (J1), second (J2) and third neighbours (J3) which in MnPSe3 are all antiferromagnetic whereas in FePSe3 J1 is ferromagnetic and J2 and J3 are antiferromagnetic.