2D nano-granularity of the oxygen chains in the YBa2Cu3O6.33 superconductor

TL;DR

This study visualizes the 2D spatial organization of oxygen chains in YBa2Cu3O6.33 superconductor, revealing a granular percolation landscape crucial for understanding its transport properties.

Contribution

It provides the first detailed visualization and characterization of oxygen chain organization in YBa2Cu3O6.33 using scanning micro X-ray diffraction.

Findings

Oxygen chains form a granular landscape of quasi-1D needles.

Segregation into Ortho II phase affects transport properties.

Percolation pattern influences superconducting behavior.

Abstract

The organization of dopants in high temperature superconductors provides complex topological geometries that controls superconducting properties. This makes the study of dopants spatial distribution of fundamental importance. The mobile oxygen ions, y, in the CuO2 plane of YBa2Cu3O6+y (0.33<y<0.67) form ordered chains which greatly affect the transport properties of the material. Here we visualize and characterize the 2D spatial organization of these oxygen chains using scanning micro X-ray diffraction measurements in transmission mode on a thin single crystal slab with y=0.33 (Tc=7 K) near the critical doping for the insulator-to-metal transition. We show the typical landscape of percolation made of a granular spatial pattern due the oxygen chains segregating in quasi-one-dimensional needles of Ortho II (O-II) phase embedded in an insulating matrix with low density of disordered oxygen interstitials