Coherently strained epitaxial YBa$_2$Cu$_3$O$_{7-\delta}$ films grown on NdGaO$_3$ (110)

TL;DR

This study demonstrates the growth of coherently strained YBa₂Cu₃O₇−δ thin films on NdGaO₃ (110) substrates, maintaining high critical temperature and reduced orthorhombicity, enabling systematic nanoengineering of high-temperature superconductors.

Contribution

It presents a method to produce coherently strained YBa₂Cu₃O₇−δ films on NdGaO₃ (110) substrates with preserved superconducting properties and reduced structural disorder.

Findings

Films are coherent up to at least 100 nm thickness.

Critical temperature of 89±1 K achieved.

Reduced orthorhombicity due to lattice matching.

Abstract

YBa$_2$Cu$_3$O$_{7-\delta}$ is a good candidate to systematically study high-temperature superconductivity by nanoengineering using advanced epitaxy. An essential prerequisite for these studies are coherently strained YBa$_2$Cu$_3$O$_{7-\delta}$ thin films, which we present here using NdGaO$_3$ (110) as a substrate. The films are coherent up to at least 100 nm thickness and have a critical temperature of 89$\pm$1 K. The $a$ and $b$ lattice parameters of the YBa$_2$Cu$_3$O$_{7-\delta}$ are matched to the in-plane lattice parameters of NdGaO$_3$ (110), resulting in a large reduction of the orthorhombicity of the YBa$_2$Cu$_3$O$_{7-\delta}$. These results imply that a large amount of structural disorder in the chain layers of YBa$_2$Cu$_3$O$_{7-\delta}$ is not detrimental to superconductivity.