Evidence of a correlation between magnetic and structural transitions in Y2-xZnxRu2O7 pyrochlore compounds

We report on an experimental investigation of the magnetic and structural properties of the Y2-xZnxRu2O7 pyrochlore system as a function of the Zn doping in the range 0.00 less than or equal to x less than or equal to 0.20. Magnetization and muon spin relaxation measurements show that the antiferromagnetic transition typical of the undoped compound at TN = 77 K is slightly reduced and broadened in the Zn doped sample. Extended X-ray absorption fine structure measurements show a peak in the Ru-O(1) first shell Debye-Waller factor at a temperature TDW approximately TN, giving evidence for a strong magnetoelastic coupling detected up to x = 0.10. A local precursor order-disorder transition at T* > TN is also observed up to x = 0.10. For x > 0.10 these local structural features are hidden due to the increasing local lattice distortion induced by the Zn2+ dopant whereas the magnetic transition is still present.