Spin-wave gap collapse in Rh-doped Sr2IrO4

Abstract

We use resonant inelastic x-ray scattering (RIXS) at the Ir L3 edge to study the effect of hole doping upon the Jeff=1/2 Mott-insulating state in Sr2IrO4, via Rh replacement of the Ir site. The spin-wave gap, associated with XY-type spin-exchange anisotropy, collapses with increasing Rh content, prior to the suppression of the Mott-insulating state and in contrast to electron doping via La substitution of the Sr site. At the same time, despite heavy damping, the d-d excitation spectra retain their overall amplitude and dispersion character. A careful study of the spin-wave spectrum reveals that deviations from the J1-J2-J3 Heisenberg used to model the pristine system disappear at intermediate doping levels. These findings are interpreted in terms of a modulation of Ir-Ir correlations due to the influence of Rh impurities upon nearby Ir wave functions, even as the single-band Jeff=1/2 model remains valid up to full carrier delocalization. They underline the importance of the transition metal site symmetry when doping pseudospin systems such as Sr2IrO4.

5 pages, 3 figures

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Cited by in corpus (7)

• Strain-engineering of the charge and spin-orbital interactions in Sr2IrO4
• Spin-wave gap collapse in Rh-doped Sr2IrO4
• Spin and charge order in doped spin-orbit coupled Mott insulators
• Magneto-synthesis effect on magnetic order, phonons, and magnons in single-crystal Sr${}_2$IrO${}_4$
• Collective mode excitations and simulated $L$-edge resonant-inelastic x-ray scattering spectra in antiferromagnetic Ca${}_2$RuO${}_4$
• Coexistence of insulator-like paramagnon and metallic spin-orbit exciton modes in SrIrO${}_3$
• A light-induced charge order mode in a metastable cuprate ladder