Resonant inelastic x-ray scattering on single magnons at oxygen $K$ edges

Rapid Communication

Resonant inelastic x-ray scattering on single magnons at oxygen $K$ edges

Beom Hyun Kim and Jeroen van den Brink

Phys. Rev. B 92, 081105(R) – Published 10 August 2015

Abstract

The recent discovery that resonant inelastic x-ray scattering can probe single-magnon (SM) dispersions in transition metal (TM) oxides when the x-ray energy is tuned to the TM $L$ edge has put this technique on a par with inelastic neutron scattering. It is generally presumed that selection rules forbid SM scattering at oxygen (O) $K$ edges. However, based on a symmetry analysis and exact diagonalization study, we show that SM scattering at O $K$ edges becomes allowed when (i) spin-orbit coupling is present in the TM $d$ shell and (ii) inversion symmetry at the O site is broken. For cuprates the resulting SM amplitude is very weak, but in iridates both prerequisites can amply be fulfilled.