Anomalous heat capacity and X-ray photoelectron spectroscopy of Superconducting FeSe1/2Te1/2

TL;DR

This study investigates the superconducting properties, heat capacity anomalies, and electronic structure of FeSe1/2Te1/2, revealing unique heat capacity behavior and hybridization effects through X-ray photoelectron spectroscopy.

Contribution

It provides new insights into the electronic structure and heat capacity anomalies of FeSe1/2Te1/2, highlighting hybridization effects and charge localization in this superconductor.

Findings

Superconducting transition temperature around 12 K.

Heat capacity shows a hump near Tc instead of a lambda transition.

XPS reveals hybridization and charge localization effects.

Abstract

The bulk polycrystalline sample FeSe1/2Te1/2 is synthesized by solid state reaction route in an evacuated sealed quartz tube at 750 oC. The presence of superconductivity is confirmed through magnetization/thermoelectric/resistivity studies. It is found that the superconducting transition temperature (Tc) is around 12 K. Heat capacity (Cp) of superconducting FeSe1-xTex exhibited a hump near Tc, instead of well defined Lambda transition. X-ray Photo electron spectroscopy (XPS) studies revealed well defined positions for divalent Fe, Se and Te but with sufficient hybridization of Fe (2p) and Se/Te (3d) core levels. In particular divalent Fe is shifted to higher BE (binding energy) and Se and Te to lower. The situation is similar to that as observed earlier for famous Cu based HTSc (High Tc superconductors), where Cu (3d) orbital hybridizes with O (2p). We also found the satellite peak of Fe at 712.00 eV, which is attributed to charge carrier localization induced by Fe at 2c site.