Investigation of the magnetic spin correlations in the layered molybdenates, Mn 2 Mo 3 O 8 and MnAMo 3 O 8 (A = Fe, Co, Zn) †

An exotic range of magnetic (and other) properties have been observed in A2Mo3O8 materials (where A is a single or mix of transition metals) making understanding their chemistry and physics timely. We have investigated the structural–property relationships in Mn2Mo3O8 and the related materials, MnFeMo3O8, MnCoMo3O8 and MnZnMo3O8. We report a detailed powder diffraction analysis confirming ferrimagnetic structures for Mn2Mo3O8 and MnFeMo3O8. Differing rates of spin ordering on crystallographically distinct sites (tetrahedral or octahedral) gives rise to magnetic hysteresis, which abruptly disappears in 2 K data. This appears to be correlated with ion displacement and/or electrostriction effects, which also relax at 2 K. We confirm an antiferromagnetic structure type for MnCoMo3O8 and no discernible magnetic ordering within the temperature range studied for MnZnMo3O8. For MnZnMo3O8 we suggest a small amount of site disorder acts to suppress magnetic ordering. This suggests that magnetic properties can be tuned both through A-site cation order and choice of A-site cations.