125Te-Mössbauer study of Fe1.1Te and FeTe0.5Se0.5 superconductor

A parent compound of iron-based superconductor, Fe1.1Te, and a Se-doped superconductor, FeTe0.5Se0.5, were investigated using 125Te-Mössbauer spectroscopy. By measuring precise temperature dependence of the spectra, discontinuous line broadening in the Fe1.1Te near the antiferromagnetic transition temperature (TN) of Fe was observed. While the broadening of the line width were observed in both samples as the temperature decreases, the temperature dependences of the line width were well reproduced as that of the recoilless fraction, assuming the Debye model with a Debye temperature of about 200 K. The discontinuous additional line broadening in the Fe1.1Te can be considered as the internal magnetic fields of Te below TN, since the temperature dependence of internal magnetic fields of Te is similar to that of Fe in 57Fe-Mössbauer spectroscopy. Therefore, hybridization of the electronic orbital of Te and Fe was suggested and the transferred magnetic moment of Te was induced through the antiferromagnetic order of Fe at TN.