Spin interactions and magnetic order in the iron oxychalcogenides BaFe2Q2O(Q=Sand Se)

The ability to tune the iron chalcogenides BaFe2Q3 from Mott insulators to metals and then superconductors with applied pressure has renewed interest in low-dimensional iron chalcogenides and oxychalcogenides. We report here a combined experimental and theoretical study on the iron oxychalcogenides BaFe2Q2O (Q = S, Se) and show that their magnetic behavior results from nearest-neighbor magnetic exchange interactions via oxide and selenide anions of similar strength, with properties consistent with more localized electronic structures than those of BaFe2Q3 systems