Synthesis, structure and properties of layered iron-oxychalcogenides Nd2Fe2Se2−xSxO3

• We have synthesized a new series of layered iron-oxychalcogenides Nd2Fe2Se2−xSxO3.
• They crystallize in layered tetragonal structure and show semiconducting behavior.
• The transport analysis indicates the polaronic transport mechanism of the carrier.
• The parent compound shows a frustrated antiferromagnetic (AFM) ground state.
• The S-substitution induces an enhanced ferromagnetic (FM) component.

A new series of sulfur-substituted iron-oxychalcogenides Nd2Fe2Se2−xSxO3 (0≤x≤0.4) was synthesized by solid state reaction method, and investigated by structure, transport, magnetic and specific heat measurements. The compounds crystallize in the layered tetragonal structure with I4/mmm space group, and show semiconducting behavior. The large discrepancy between the activation energies for conductivity, Eρ (152–202 meV), and thermopower, ES (15.6–39.8 meV), indicates the polaronic transport mechanism of the carrier. The parent compound Nd2Fe2Se2O3 exhibits a frustrated antiferromagnetic (AFM) ground state, and the S-substitution induces an enhanced ferromagnetic (FM) component and possible increased degree of frustration.

The crystal structure of Nd2Nd2Fe2Se2−xSxO3 is built up by stacking fluorite-like Nd2O2 layers and anti-CuO2-type Fe2O(Se/S)2 layers with Fe2+ cations coordinated by two in-plane O2- and four Se2- above and below the square Fe2O plane.Figure optionsDownload as PowerPoint slide