Momentum-resolved lattice dynamics of parent and electron-doped Sr${}_2$IrO${}_4$

Abstract

The mixing of orbital and spin character in the wave functions of the $5d$ iridates has led to predictions of strong couplings among their lattice, electronic and magnetic degrees of freedom. As well as realizing a novel spin-orbit assisted Mott-insulating ground state, the perovskite iridate Sr${}_2$IrO${}_4$ has strong similarities with the cuprate La${}_2$CuO${}_4$, which on doping hosts a charge-density wave that appears intimately connected to high-temperature superconductivity. These phenomena can be sensitively probed through momentum-resolved measurements of the lattice dynamics, made possible by meV-resolution inelastic x-ray scattering. Here we report the first such measurements for both parent and electron-doped Sr${}_2$IrO${}_4$. We find that the low-energy phonon dispersions and intensities in both compounds are well described by the same nonmagnetic density functional theory calculation. In the parent compound, no changes of the phonons on magnetic ordering are discernible within the experimental resolution, and in the doped compound no anomalies are apparent due to charge-density waves. These measurements extend our knowledge of the lattice properties of (Sr${}_{1-x}$La${}_x$)${}_2$IrO${}_4$ and constrain the couplings of the phonons to magnetic and charge order.

arXiv comment8 pages, 6 figures (+ 12 pages, 6 figures of supplemental material)

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Cited by in corpus (4)

• A Hubbard exciton fluid in a photo-doped antiferromagnetic Mott insulator
• High-pressure synthesis of Ba${}_2$RhO${}_4$, a rhodate analogue of the layered perovskite Sr-ruthenate
• Evolution of electronic and magnetic properties of Sr${}_2$IrO${}_4$ under strain
• Absence of temperature-dependent phonon anomalies in Sr2IrO4 and Sr3Ir2O7