Spin-phonon coupling in hole-doped pyrochlore iridates Y2(Ir1-xRux)2O7 : A Raman scattering study

Temperature dependent Raman scattering measurements have been performed to explore unusual coupling between magnetism and crystal structure in doped pyrochlore iridate Y-2(Ir1-xRux)(2)O-7 with x = 0.0, 0.05 and 0.2. The parent Y2Ir2O7 shows an onset of magnetic ordering around similar to 160K (T-N) which monotonically decreases with Ru doping. Further, magnetic moment also decreases with progressive substitution of Ru. Substitution of Ru (4+) (4d(4)) for Ir4+ (5d(5)) does not introduce significant modification in structural parameters, however, the magnetic transition temperature decreases systematically with doping. Raman scattering data show an anomalous change in A(1g) and P-3 Raman mode frequency and line-width across T-N of individual samples. We further show that the shifting of Raman mode frequency with temperature exhibits a strong deviation from an harmonic decay around and below the T-N of respective samples which underlines a spin-phonon coupling in these materials.