Evolution of Superconductivity in Fe$_{1+y}$Te$_{1-x}$Se$_{x}$ Annealed in Te Vapor

TL;DR

This study demonstrates that Te vapor annealing effectively induces bulk superconductivity in Fe$_{1+y}$Te$_{1-x}$Se$_{x}$ crystals by removing excess Fe, with optimal conditions leading to high critical current densities.

Contribution

It provides a detailed analysis of how Te vapor annealing modulates superconductivity in Fe$_{1+y}$Te$_{1-x}$Se$_{x}$, revealing optimal annealing conditions and effects on charge carriers.

Findings

Superconductivity is induced by Te vapor annealing up to a molar ratio of 1:10.

Annealing removes excess Fe, delocalizing charge carriers.

Optimal annealing yields high critical current densities (~4.3×10^5 A/cm^2).

Abstract

We report a detailed study of the Te vapor annealing effect in Fe$_{1+y}$Te$_{0.6}$Se$_{0.4}$ single crystals. Bulk superconductivity can be gradually induced by annealing with increasing amount of Te, until the molar ratio of Te to the sample reaches 1 : 10. By further increasing Te molar ratio, superconducting volume is gradually reduced. Resistivity and Hall effect measurements manifest that annealing in Te vapor delocalizes the charge carriers by removing excess Fe. The optimally Te annealed crystal shows homogeneous critical current densities with a large value of $\sim$ 4.3 $\times$ 10$^5$ A/cm$^2$, which proves that the Te annealing is effective to induce bulk superconductivity in Fe$_{1+y}$Te$_{1-x}$Se$_{x}$.