Contrasting antiferromagnetic order between FePS 3 and MnPS 3

Transition-metal thiophosphates, MPS3 (M = Fe, Mn, etc.), make up a class of antiferromagnetic materials with quasi-two-dimensional magnetic behaviour. The metal atoms occupy a honeycomb lattice. In MnPS3, the first-neighbour interaction is 400 times stronger than the exchange between the planes and the Mn moments show little anisotropy. The antiferromagnetic order is not well established perpendicular to the planes. Here we present the first powder neutron diffraction patterns of FePS3. The absence of trailing edges on the magnetic Bragg peaks, such as have been observed in MnPS3, indicates that the magnetic order is three-dimensional in FePS3.