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

Abstract A new series of sulfur-substituted iron-oxychalcogenides Nd 2 Fe 2 Se 2− x S x O 3 (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 I 4/ mmm space group, and show semiconducting behavior. The large discrepancy between the activation energies for conductivity, E ρ (152–202 meV), and thermopower, E S (15.6–39.8 meV), indicates the polaronic transport mechanism of the carrier. The parent compound Nd 2 Fe 2 Se 2 O 3 exhibits a frustrated antiferromagnetic (AFM) ground state, and the S-substitution induces an enhanced ferromagnetic (FM) component and possible increased degree of frustration.