Origin of the critical scattering on two length scales inSrTiO3: A high-energy synchrotron-radiation diffraction study

Abstract

High-q-resolution diffraction experiments performed with 100 keV synchrotron radiation on the identical ${\mathrm{SrTiO}}_3$ crystal used in neutron and x-ray-scattering experiments before, unambiguously show that the bulk critical scattering above ${\mathit{T}}_{\mathit{c}}$=99.5 K does not exhibit a sharp component, which had been found in recent x-ray-diffraction experiments. The observed temperature dependence of the inverse correlation length is in excellent agreement with the neutron data. However, scattering on two length scales was observed in a near-surface volume element of the same crystal.