Unraveling Orbital Correlations via Magnetic Resonant Inelastic X-ray Scattering

TL;DR

This paper demonstrates that magnetic RIXS can effectively probe orbital correlations in transition metal compounds, revealing orbital order and dynamics that are difficult to access with neutron scattering.

Contribution

The study provides a detailed calculation showing how magnetic RIXS intensity depends on orbital symmetry and polarization, enabling differentiation of orbital states.

Findings

RIXS intensity is sensitive to orbital symmetry and photon polarization.

Magnetic RIXS can distinguish between orbital ordered and liquid states.

Orbital correlations can be directly accessed via RIXS measurements.

Abstract

Although orbital degrees of freedom are a factor of fundamental importance in strongly correlated transition metal compounds, orbital correlations and dynamics remain very difficult to access, in particular by neutron scattering. Via a direct calculation of scattering amplitudes we show that instead magnetic resonant inelastic x-ray scattering (RIXS) does reveal orbital correlations. In contrast to neutron scattering, the intensity of the magnetic excitations in RIXS depends very sensitively on both the symmetry of the orbitals that spins occupy, and on photon polarizations. We show in detail how this effect allows magnetic RIXS to distinguish between alternating orbital ordered and ferro-orbital (or orbital liquid) states.