Magnetic excitations in hole-doped Sr2IrO4: A comparison with electron-doped cuprates

Abstract

We have studied the evolution of magnetic and orbital excitations as a function of hole-doping in single crystal samples of Sr2Ir(1-x)Rh(x)O4 (0.07 < x < 0.42) using high resolution Ir L3-edge resonant inelastic x-ray scattering (RIXS). Within the antiferromagnetically ordered region of the phase diagram (x < 0.17) we observe highly dispersive magnon and spin-orbit exciton modes. Interestingly, both the magnon gap energy and the magnon bandwidth appear to increase as a function of doping, resulting in a hardening of the magnon mode with increasing hole doping. As a result, the observed spin dynamics of hole-doped iridates more closely resemble those of the electron-doped, rather than hole-doped, cuprates. Within the paramagnetic region of the phase diagram (0.17 < x < 0.42) the low-lying magnon mode disappears, and we find no evidence of spin fluctuations in this regime. In addition, we observe that the orbital excitations become essentially dispersionless in the paramagnetic phase, indicating that magnetic order plays a crucial role in the propagation of the spin-orbit exciton.

10 pages, 9 figures

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Cited by in corpus (6)

• Superconductivity in high-$T_c$ and related strongly correlated systems from variational perspective: Beyond mean field theory
• Strain-engineering of the charge and spin-orbital interactions in Sr2IrO4
• High-resolution resonant inelastic x-ray scattering study of the electron-phonon coupling in honeycomb $\alpha$-Li${}_2$IrO${}_3$
• Spin-wave gap collapse in Rh-doped Sr2IrO4
• Spin-orbit excitons in a correlated metal: Raman scattering study of Sr2RhO4
• Coexistence of insulator-like paramagnon and metallic spin-orbit exciton modes in SrIrO${}_3$