Transitions in Sr 2 Ru x Ir 1 − x O 4 compounds studied by the 99 Ru Mössbauer effect

The ${}^{99}\mathrm{Ru}$ M\ossbauer effect has been measured in the ${\mathrm{Sr}}_{2}{\mathrm{Ru}}_{x}{\mathrm{Ir}}_{1\ensuremath{-}x}{\mathrm{O}}_{4}$ system for $x=1.0,$ 0.7, 0.5, and 0.4 at 4.2 K. The isomer shift measurements show a change of -0.05(.02) mm/s as the compound changes from a metal $(x=0.7)$ to an insulator $(x=0.5).$ This isomer shift change is the electronic signature of the metal-insulator transition. All these spectra are single line. At $x=0.4$ the compound undergoes a magnetic phase transition with the measurement of a hyperfine magnetic field of 7.2(1.5) T. The ${}^{99}\mathrm{Ru}$ M\ossbauer effect has been measured from 1.8 to 147.5 K for ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ and from these measurements the Debye temperature was estimated to be 427(50) K.