Strong anisotropy within a Heisenberg model in the J=1/2 insulating state of Sr2Ir0.8Ru0.2O4

Abstract

The dispersive magnetic excitations in Sr2IrO4 have previously been well described within an isospin-1/2 Heisenberg model on a square lattice that revealed parallels with La2CuO4. Here we investigate the inelastic spectra of Sr2Ir0.8Ru0.2O4 with resonant inelastic x-ray scattering (RIXS) at the Ir L3-edge. The results are well described using linear spin-wave theory within a similar Heisenberg model applicable to Sr2IrO4, however the disorder induced by the substitution of 20% Ir4+ ions for Ru4+ removes longer range exchange interactions. A large spin-gap (40 meV) is measured indicating strong anisotropy from spin-orbit coupling that is manifest due to the altered magnetic structure in Sr2Ir0.8Ru0.2O4 with c-axis aligned moments compared to the basal plane moments in the parent. Collectively the results indicate the robustness of a Heisenberg model description even when the magnetic structure is altered and the J=1/2 moments diluted.

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Cited by in corpus (5)

• Spin-orbit-controlled metal-insulator transition in Sr${}_2$IrO${}_4$
• Raman scattering study of vibrational and magnetic excitations in Sr${}_{2-x}$La${}_x$IrO${}_4$
• Spin-gap and two-dimensional magnetic excitations in Sr2IrO4
• Comprehensive Control of Metamagnetic Transition of Antiferromagnetic Mott Insulator Sr2IrO4 by in-situ Anisotropic Strain
• Overdamped antiferromagnetic strange metal state in Sr${}_3$IrRuO${}_7$