Resonant X-rays at the Cu L-edge as a momentum dependent probe of the magnetic excitation spectrum in cuprates

TL;DR

This paper demonstrates that resonant inelastic x-ray scattering at the Cu L-edge can directly probe momentum-dependent magnetic excitations in cuprates, positioning RIXS as a comparable technique to neutron scattering.

Contribution

It reveals that direct spin-flip scattering is possible in RIXS at the Cu L- and M-edges and details how this can be used to study magnetic properties in cuprates.

Findings

RIXS at Cu L-edge can directly measure magnetic excitations.

Computed magnetic scattering amplitudes match experimental intensities.

RIXS is comparable to neutron scattering for magnetic studies.

Abstract

We show that, contrary to common lore, in resonant inelastic x-ray scattering (RIXS) at the copper L- and M-edge direct spin-flip scattering is in principle allowed. We demonstrate how this possibility can be exploited to probe the momentum dependent magnetic properties of cuprates such as the high Tc superconductors and compute in detail the relevant local and momentum dependent magnetic scattering amplitudes, which we compare to the elastic and $dd$-excitation scattering intensities. For cuprates these results put RIXS as a technique on the same footing as neutron scattering.