Electronic, magnetic properties and chemical bonding in layered oxychalcogenides Ca4Fe2Cu2S2O6 and Ca4Fe2Cu2Se2O6 from first principles calculations

The crystal structure, electronic, magnetic properties and inter-atomic bonding in recently synthesized five-component Fe-containing oxychalcogenides Ca4Fe2Cu2Ch2O6, where Ch are S or Se, which unlike all other related materials contain Fe atoms in 2D perovskite-like oxide blocks (Ca4Fe2O6), were probed by means of first-principle FLAPW-GGA calculations. We found that these materials can be characterized as antiferromagnetic ionic semiconductors, composed of alternating non-magnetic chalcogenide blocks (Cu2Ch2) and antiferromagnetic oxide blocks (Ca4Fe2O6) with S-AFM spin configuration for Fe sublattice; the interaction between these building blocks is ionic. Moreover, our results reveal that for these materials the formation of “natural multiple quantum wells” can be expected — like it has been found for more simple four-component LnCuOCh phases. This feature (unique for five-component Fe-containing phases) originates from 2D density of states and quantum size effects in these layered materials.

The scheme of energy band structures for Ca4Fe2Cu2S2O6 in the near-Fermi region. The band gap values are given.Figure optionsDownload as PowerPoint slideHighlights
► Very recently the new oxychalcogenides Ca4Fe2Cu2Ch2O6 were synthesized.
► Electronic, magnetic properties for these phases were probed from first principles.
► These materials are characterized as antiferromagnetic ionic semiconductors.
► For these materials the “natural multiple quantum wells” are predicted.
► Bonding includes ionic and covalent contributions and is highly anisotropic.