Bulk superconductivity in FeTe$_{1-x}$Se$_{x}$ via physicochemical pumping of excess iron

TL;DR

This paper introduces a new physicochemical method to remove excess iron impurities from FeTe$_{1-x}$Se$_{x}$, enabling the realization of bulk superconductivity in this topological superconductor candidate.

Contribution

A novel physicochemical process for efficiently removing interstitial iron impurities, improving the synthesis of high-quality FeTe$_{1-x}$Se$_{x}$ crystals with enhanced superconducting properties.

Findings

Successful removal of excess iron impurities.

Achievement of bulk superconductivity in FeTe$_{1-x}$Se$_{x}$.

Enhanced superconducting volume fractions in treated samples.

Abstract

The iron-based superconductor FeTe$_{1-x}$Se$_{x}$ has attracted considerable attention as a candidate topological superconductor owing to a unique combination of topological surface states and bulk high-temperature superconductivity. The superconducting properties of as-grown single crystals, however, are highly variable and synthesis dependent due to excess interstitial iron impurities incorporated during growth. Here we report a novel physicochemical process for pumping this interstitial iron out of the FeTe$_{1-x}$Se$_{x}$ matrix and achieving bulk superconductivity. Our method should have significant value for the synthesis of high-quality single crystals of FeTe$_{1-x}$Se$_{x}$ with large superconducting volume fractions.