Bulk Superconductivity in Fe1+yTe0.6Se0.4 Induced by Removal of Excess Fe

TL;DR

This study demonstrates that arsenic vapor annealing effectively induces bulk superconductivity in Fe1+yTe0.6Se0.4 by removing excess Fe, leading to improved superconducting properties confirmed through various measurements.

Contribution

It reveals that arsenic vapor annealing removes excess Fe and enhances superconductivity without doping, providing a new method for optimizing Fe-based superconductor performance.

Findings

Arsenic vapor annealing induces bulk superconductivity in Fe1+yTe0.6Se0.4.

The process removes excess Fe without doping or intercalation.

Superconducting critical current density becomes isotropic, large, and homogeneous.

Abstract

Experimental evidences from transport, magnetic, and magneto-optical (MO) image measurements confirmed that arsenic (As) vapor annealing was another effective way to induce bulk superconductivity with isotropic, large, and homogenous superconducting critical current density (Jc) in Fe1+yTe0.6Se0.4 single crystal. Since As is an exotic and easily detectable heavy element to Fe1+yTe0.6Se0.4 single crystal, As vapor annealing is very advantageous for the study of annealing mechanism. Detailed micro-structural and elemental analyses exclude the possibility that intercalating or doping effect may happen in the other post-annealing methods, proving that Fe reacts with As on the surface of the crystal and the reaction itself acts as a driving force to drag excess Fe out. The removal of excess Fe results in the good superconductivity performance.