Anisotropic dynamical scaling in a weakly 3D system: The case of oxygen ordering in

¹ Condensed Matter Physics and Chemistry Department, Risø National Laboratory DK-4000 Roskilde, Denmark
² HASYLAB - Notkestraße 85, D-22603, Germany
³ Materials Research Department, RisøNational Laboratory DK-4000 Roskilde, Denmark
⁴ Forschungszentrum Karlsruhe, ITP - D-76021, Germany

Corresponding author: kall@fy.chalmers.se.

Received: 6 January 2000
Accepted: 9 June 2000

Abstract

The coarsening of anisotropic oxygen superstructure domains of the Ortho-II type in YBa₂Cu₃O_6.5 has been investigated by high-energy X-ray and neutron diffraction. The time dependence of the scattering function was probed after quenches through the Ortho-II phase transition, and by room temperature measurements of after various sample annealing histories. The data are well accounted for by a Lorentzian-squared–type scattering function. In agreement with the scaling hypothesis, we find that the integrated intensity is independent of time, and the domain growth is described by a single scalar function that characterise the time evolution of the anisotropic correlation lengths. We have thus for the first time demonstrated the applicability of the dynamical scaling hypothesis in a real system of high complexity and intermediate dimensionality.