Probing single magnon excitations in Sr$_2$IrO$_4$ using O $K$-edge resonant inelastic X-ray scattering

TL;DR

This paper demonstrates that oxygen K-edge RIXS can effectively probe single magnon excitations in Sr$_2$IrO$_4$, offering a new method for studying magnetic excitations in heavy element systems with better energy resolution.

Contribution

It introduces a novel application of oxygen K-edge RIXS to measure single magnon excitations in iridates, expanding the technique's utility beyond transition metal L-edges.

Findings

Single magnon excitations observed at the oxygen K-edge in Sr$_2$IrO$_4$

Oxygen K-edge RIXS provides a viable alternative for magnetic studies in heavy element systems

Potential for broader application to various magnetic materials with strong spin-orbit coupling

Abstract

Resonant inelastic X-ray scattering (RIXS) at the $L$-edge of transition metal elements is now commonly used to probe single magnon excitations. Here we show that single magnon excitations can also be measured with RIXS at the $K$-edge of the surrounding ligand atoms when the center heavy metal elements have strong spin-orbit coupling. This is demonstrated with oxygen $K$-edge RIXS experiments on the perovskite Sr$_2$IrO$_4$, where low energy peaks from single magnon excitations were observed. This new application of RIXS has excellent potential to be applied to a wide range of magnetic systems based on heavy elements, for which the $L$-edge RIXS energy resolutions in the hard X-ray region is usually poor.