It is well known that the existence of interstitial Fe is a great obstacle to enhancing the superconducting properties of the Fe(Se, Te) system. In this work, a silver and oxygen codoping effect toward enhancement of the superconductivity and flux pinning in Fe(Se, Te) bulks is reported. The oxygen ions from SeO2 can induce the precipitation of interstitial Fe as Fe2O3, thus simultaneously optimizing the superconducting properties of Fe(Se, Te) and forming extra flux pinning centers, while the existence of Ag can enhance the intergrain connections of the polycrystalline material by improving the electron transport at grain boundaries. Compared with the undoped sample, the critical current density, the upper critical field, and the thermally activated flux flow activation energy are greatly enhanced by 4.7, 1.7, and 1.5 times, respectively. The novel synthesis technique and optimized properties of this work can pave the way for the development of high-performance Fe(Se, Te) superconduct
Abstract
Since the discovery of iron-based superconductors, a new chapter has been opened in the history of the development of high temperature superconductivity. In the past decade, there have been remarkable achievements in the theory, experiments, and applications of iron-based superconductors, and our understanding of the mechanism of superconductivity has been deeply enriched. Here, we review the research progress on high-pressure studies on the superconductivity, flux pinning, and vortex dynamics of iron-based superconductor families. The topics include pressure-induced superconductivity, raising the superconducting transition temperature, pressure-induced elimination and re-emergence of superconductivity, the effects of phase separation on superconductivity, increasing the critical current density, significantly suppressing vortex creep, and reducing the size of the flux bundles.