Atomic-scale identification of novel planar defect phases in heteroepitaxial YBa$_2$Cu$_3$O$_{7-\delta}$ thin films

TL;DR

This study identifies two new types of planar defects in heteroepitaxial YBCO thin films, which could influence their superconducting properties, using advanced electron microscopy techniques.

Contribution

The paper reports the discovery and atomic-scale characterization of novel planar defect phases in YBCO thin films grown by pulsed-laser deposition.

Findings

Two novel planar defect types identified in YBCO films.

Defects involve intergrowths of BaO and Y-O layers.

Potential impact on high-$T_c$ superconductivity.

Abstract

We have discovered two novel types of planar defects that appear in heteroepitaxial YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO123) thin films, grown by pulsed-laser deposition (PLD) either with or without a La$_{2/3}$Ca$_{1/3}$MnO$_3$ (LCMO) overlayer, using the combination of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging and electron energy loss spectroscopy (EELS) mapping for unambiguous identification. These planar lattice defects are based on the intergrowth of either a BaO plane between two CuO chains or multiple Y-O layers between two CuO$_2$ planes, resulting in non-stoichiometric layer sequences that could directly impact the high-$T_c$ superconductivity.