Physical properties of the layered oxypnictide Sr₂ScFeAsO₃: a Mössbauer study down to 1.7 K

A polycrystalline sample of Sr₂ScFeAsO₃was studied by⁵⁷Fe Mössbauer spectroscopy down to 1.7 K. In contrast to the earlier Mössbauer data, the obtained in this work results indicate that Sr₂ScFeAsO₃is in paramagnetic state down to 10 K, while the spectra recorded at 4.6 K and 1.7 K show a weak magnetic order of Fe moments in the Fe₂As₂layers. Temperature dependences of isomer shift and quadrupole splitting/shift are compared with specific heat and electrical resistivity data from earlier investigations revealing different local Debye temperatures for the Fe₂As₂and perovskite-related Sr₂ScO₃layers. Finally, a fast decrease of the carrier density was observed below 80 K and this effect seems to be responsible for the absence of superconductivity in the studied compound.