Temperature-dependent x-ray diffraction study of Pd/Cu site interchange in non-Fermi liquid UCu(4)Pd

A pair distribution function (PDF) analysis of temperature-dependent x-ray diffraction measurements from UCu$_4$Pd is presented. Fits to the displacement parameters ($u^2$'s) with a Debye model show better agreement with a model that includes 25\ percent of the Pd atoms on 16$e$ (Cu) sites. In addition, significant non-thermal disorder is observed in the Cu environment, in contrast to previous measurements of local order in the U-Cu pairs