Annealing effects on superconductivity and magnetism in Fe1+yTe1−xSx single crystals

Abstract

The annealing effects on superconductivity and magnetism in Fe1 + yTe1−xSx single crystals have been investigated. It is found that the superconductivity is improved not only by annealing in air but also by annealing in vacuum or argon. In addition, even for a low S content sample with long-range magnetic order, the superconductivity is also obviously improved by air annealing. These are inconsistent with the previous results of other groups. In the air annealing case, energy dispersive x-ray spectrometer analyses and heat capacity results show that oxygen is incorporated into the system and the long-range magnetic order is partially suppressed. In contrast, for vacuum or argon annealing, no change of composition is detected and no other ions are incorporated, and the enhancement of superconductivity clearly indicates that the modulation of the microstructure plays an important role in the annealing effect on superconductivity and magnetism.