Superconducting FeSe_1−<i>x</i>Te_<i>x</i> Single Crystals Grown by Optical Zone-Melting Technique

Abstract

A new approach to grow FeSe 1− x Te x single crystals with an optical zone-melting technique was successfully employed. Crystals with actual composition 0.4 ≤ x ≤ 1.0 all show high crystallinity with no phase separation. The ability to visually observe the locally heated melt, and ease of use and control of the image furnace make this method a promising and time-efficient way for obtaining high-quality FeSe 1− x Te x crystals. Our results indicate that with adequate heat treatment, the nonuniform distribution of Se and Te atoms in crystal lattice can be effectively eliminated, while the transition width of superconductivity can be reduced to about 2 K, which suggest the crystals are homogeneous in nature.