Multiscale distribution of oxygen puddles in 1/8 doped $YBa_{2}Cu_{3}O_{6.67}$
摘要
Abstract Despite intensive research a physical explanation of high T c superconductors remains elusive. One reason for this is that these materials have generally a very complex structure making useless theoretical models for a homogeneous system. Little is known on the control of the critical temperature by the space disposition of defects because of lack of suitable experimental probes. X-ray diffraction and neutron scattering experiments used to investigate y oxygen dopants in YBa 2 Cu 3 O 6+y lack of spatial resolution. Here we report the spatial imaging of dopants distribution inhomogeneity in YBa 2 Cu 3 O 6.67 using scanning nano X-ray diffraction. By changing the X-ray beam size from 1 micron to 300 nm of diameter, the lattice inhomogeneity increases. The ordered oxygen puddles size distribution vary between 6–8 nm using 1 × 1 μm 2 beam, while it is between 5–12 nm with a fat tail using the 300 × 300 nm 2 beam. The increased inhomogeneity at the nanoscale points toward a network of superconducting puddles made of ordered oxygen interstitials.