Single Crystal Growth of Cuprate Superconductor (Lu$_{0.8}$Nd$_{0.2}$)Ba$_2$Cu$_4$O$_8$ by KOH Flux Method

TL;DR

This paper reports the successful growth of Nd-substituted LuBa2Cu4O8 single crystals using the KOH flux method, revealing superconductivity at around 75 K and structural details of the mixed rare-earth site.

Contribution

First demonstration of Nd substitution in LuBa2Cu4O8 single crystals with detailed structural and superconducting property analysis.

Findings

Nd partially occupies Lu site in the crystal structure.

Superconducting transition observed at ~75 K.

The c-axis lattice parameter matches that of Tm124.

Abstract

Single crystals of Nd-substituted LuBa$_2$Cu$_4$O$_8$ were successfully grown by the KOH flux method. The single phase of Lu$_{1-x}$Nd$_x$Ba$_2$Cu$_4$O$_8$ [(Lu,Nd)124] formed at $x = 0.2$. The compound crystallized as orthorhombic Ammm structure with lattice constants of a = 3.835(3) {\AA}, b = 3.879(2) {\AA} and c = 27.195(6) {\AA}. Single crystal structural analysis demonstrated that the Nd ion partially occupied the Lu site. The (Lu,Nd)124 exhibited the superconducting transition at ~75 K in the magnetic susceptibility and resistivity. The $T_c$ and the c-axis of the (Lu,Nd)124 corresponded to Tm124. These results indicate that RE124 equivalent to the one composed of single RE element is obtained by combination of two RE elements.