Quenching Dependence on Superconductivity in the Synthesizing Process of Single Crystals of Rb$_x$Fe$_{2-y}$Se$_2$

TL;DR

This study investigates how the quenching rate affects the superconducting properties and surface microstructure of Rb$_x$Fe$_{2-y}$Se$_2$ single crystals, revealing that faster cooling enhances superconductivity and connectivity.

Contribution

It demonstrates the direct influence of cooling rate on superconducting transition temperature and microstructure in Rb$_x$Fe$_{2-y}$Se$_2$ crystals, providing insights for optimizing synthesis.

Findings

Higher cooling rates increase superconducting transition temperature.

Faster cooling results in a connected superconducting mesh-like structure.

Slow cooling causes isolation of superconducting domains.

Abstract

Superconducting single crystals of Rb-intercalated FeSe compounds Rb$_x$Fe$_{2-y}$Se$_2$ were prepared by using a starting material of Rb$_2$Se as a Rb source. The superconducting properties and the surface microstructures were systematically controlled by varying the cooling rate in the quenching process. The higher cooling rate in the sample provided a higher superconducting transition temperature with highly connected superconducting mesh-like surface structure. Extremely slow-cooling process led to the complete isolation between the superconducting domains.