Scanning micro-x-ray diffraction unveils the distribution of oxygen chain nanoscale puddles in YBa 2Cu3O6.33

Oxygen chain fragments are known to appear at the insulator-to-superconductor transition in YBa 2 Cu 3 O 6 + y . However, the self-organization and the size distribution of oxygen chain fragments are not known. Here, we seek to fill this gap, using scanning micro-x-ray diffraction, which is an imaging method based on advances in focusing a synchrotron radiation beam. This approach allows us to probe both real-space and k -space of high-quality YBa 2 Cu 3 O 6.33 single crystals with T c = 7 K. We report compelling evidence for nanoscale striped puddles, with Ortho-II structure, made of chain fragments in the basal Cu(1) plane with local oxygen concentration y ≥ 0.5. The size of the Ortho-II puddles spans a range between 2 and 9 nm. The real-space imaging of Ortho-II puddles granular network shows that superconductivity, at a low hole-doping regime, occurs in a network of nanoscale oxygen ordered patches, interspersed with oxygen depleted regions. The manipulation by thermal treatments of the striped Ortho-II puddles has been investigated focusing on the spontaneous symmetry breaking near the order-to-disorder phase transition at T0= 350 K.