Flux-free growth of large superconducting crystal of FeSe by traveling-solvent floating-zone technique

TL;DR

This paper reports a novel flux-free method using traveling-solvent floating-zone technique to grow large, high-quality superconducting FeSe crystals with homogeneous composition and confirmed bulk superconductivity.

Contribution

It introduces a new flux-free growth process for large FeSe crystals, achieving sizes and quality surpassing previous methods.

Findings

Crystals up to 15x6x2 mm3 in size.

Superconducting transition temperature of 9.4 K.

Nearly perfect diamagnetic shielding of -97%.

Abstract

A flux-free solution to the growth of large and composition homogeneous superconducting FeSe crystal is reported for the first time, which is based on the traveling-solvent floating-zone technique. The size of the crystal samples prepared by this approach is up to 15x6x2 mm3, being far bigger than previously reported in all dimensions, and the main phase of the crystals is of a single preferred orientation along the tetragonal (101) plane. X-ray diffraction analysis identifies the main phase to be the superconducting tetragonal \b{eta}-FeSe. The superconducting transition temperature (TC) is determined to be 9.4 K by AC magnetic susceptibility and electronic transport measurements. A nearly perfect diamagnetic shielding of -97% is observed, indicating a bulk superconductivity in the crystal sample.