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

Abstract

We report on an experimental investigation of the magnetic and structural properties of the Y_2−xZn_xRu₂O₇ pyrochlore system as a function of the Zn doping in the range 0.00 ≤ x ≤ 0.20. Magnetization and muon spin relaxation measurements show that the antiferromagnetic transition typical of the undoped compound at T_N = 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 T_DW ≈ T_N, giving evidence for a strong magnetoelastic coupling detected up to x = 0.10. A local precursor order–disorder transition at T* > T_N 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.