Marinite Li2M(SO4)2 (M = Co, Fe, Mn) and Li1Fe(SO4)2: Model Compounds for Super-Super-Exchange Magnetic Interactions

New materials initially designed for battery electrodes are often of interest for magnetic study, because their chemical compositions include 3d transition metals. We report here on the magnetic properties of marinite phases Li2M(SO4)(2) (M = Fe, Co, Mn) and Li1Fe(SO4)(2), which all order antiferromagnetically at low temperature. From neutron powder diffraction, we propose a model for their ground-state magnetic structures. The magnetism of marinite Li2M(SO4)(2) compounds unambiguously results from super-super-exchange interactions; therefore, these materials can be considered as a model case for which the Goodenough-Kanamori-Anderson rules can be tested.