Abstract:
Temperature (12 K less than or equal to T less than or equal to 300 K) dependent extended x-ray absorption fine structure (EXAFS) studies at the Fe K edge in FeSe(1-x)Te(x) (x = 0, 0.5 and 1.0) compounds have been carried out to understand the reasons for the increase in TC upon Te doping in FeSe. While local distortions are present near superconducting onset in FeSe and FeSe(0.5)Te(0.5), they seem to be absent in non-superconducting FeTe. Of crucial importance is the variation of anion height. In FeSe(0.5)Te(0.5), near the superconducting onset, the two heights, h(Fe-Se) and h(Fe-Te) show a nearly opposite behaviour. These changes indicate a possible correlation between Fe-chalcogen hybridization and the superconducting transition temperature in these Fe-chalcogenides.
