Overdamped antiferromagnetic strange metal state in Sr${}_3$IrRuO${}_7$

Abstract

The unconventional electronic ground state of Sr${}_3$IrRuO${}_7$ is explored via resonant x-ray scattering techniques and angle-resolved photoemission measurements. As the Ru content approaches $x=0.5$ in Sr${}_3$(Ir${}_{1-x}$Ru${}_x$)${}_2$O${}_7$, intermediate to the $J_{eff}=1/2$ Mott state in Sr${}_3$Ir${}_2$O${}_7$ and the quantum critical metal in Sr${}_3$Ru${}_2$O${}_7$, a thermodynamically distinct metallic state emerges. The electronic structure of this intermediate phase lacks coherent quasiparticles, and charge transport exhibits a linear temperature dependence over a wide range of temperatures. Spin dynamics associated with the long-range antiferromagnetism of this phase show nearly local, overdamped magnetic excitations and an anomalously large energy scale of 200 meV---an energy far in excess of exchange energies present within either the Sr${}_3$Ir${}_2$O${}_7$ or Sr${}_3$Ru${}_2$O${}_7$ solid-solution endpoints. Overdamped quasiparticle dynamics driven by strong spin-charge coupling are proposed to explain the incoherent spectral features of the strange metal state in Sr${}_3$IrRuO${}_7$.

5 pages, 4 figures

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Cited by in corpus (1)

• Spin-orbit excitons and electronic configuration of the $5d^4$ insulator Sr${}_3$Ir${}_2$O${}_7$F${}_2$