The regulation of superconducting properties of Fe(Se, Te) crystal by oxygen doping

Trace oxygen-doped FeSe 0.4 Te 0.6 single crystals were synthesized using the self-flux method to investigate the effects of oxygen incorporation on their crystal structure, superconducting transition, and flux pinning properties. Experimental results indicate that trace O-doping effectively modulates the superconducting transition temperature ( T c ) and enhances the critical current density ( J c ), with a more pronounced improvement in current-carrying capacity observed under high magnetic fields. Based on the Dew–Hughes model analysis, the sample with 0.5% O-doping exhibits the most robust pinning effect. This study demonstrates that trace oxygen doping can effectively optimize the superconducting performance of FeSe 0.4 Te 0.6 and reveals the existence of an optimal doping regime, which provides valuable insights into the mechanism and practical application of iron-based superconductors.