High-pressure growth of fluorine-free SmFeAsO$_{1-x}$ superconducting single crystals

TL;DR

This paper reports the successful high-pressure growth of fluorine-free SmFeAsO$_{1-x}$ superconducting single crystals, demonstrating their high quality and superconducting transition at 53.5 K using a self-flux method.

Contribution

It introduces a novel high-pressure synthesis technique for fluorine-free SmFeAsO$_{1-x}$ crystals, achieving high-quality samples with well-defined structure and superconducting properties.

Findings

Crystals grown at 3.3 GPa and 1350-1450°C show superconductivity at 53.5 K.

The crystals have a well-defined layered tetragonal structure.

High-quality crystal structure confirmed by synchrotron X-ray and electron microscopy.

Abstract

Superconducting single crystals of SmFeAsO$_{1-x}$ without fluorine doping were grown at a pressure of 3.3 GPa and a temperature of 1350-1450 $^\circ$C by using the self-flux method. Plate-like single crystals of a few-150 $\mu$m in their lateral size were obtained. Single crystals showed the superconducting transition at about 53.5 K with a narrow transition width of 0.5 K. The synchrotron-irradiated x-ray diffractometry patterns and high-angle-annular-dark-field scanning transmission electron microscopy images point to the high quality of the crystals with a well-defined layered tetragonal structure. The chemical compositions of the crystals were estimated by using the electron-probe x-ray microanalysis.