Ultrafast dynamics of spin and orbital correlations in quantum materials: an energy- and momentum-resolved perspective

TL;DR

This paper introduces time-resolved resonant inelastic X-ray scattering (trRIXS) as a powerful technique to study ultrafast charge, spin, and orbital dynamics in quantum materials, revealing transient correlations and interactions.

Contribution

It presents the principles, instrumentation, and first observations of transient antiferromagnetic correlations using trRIXS, advancing the study of out-of-equilibrium quantum states.

Findings

First observation of transient antiferromagnetic correlations in a photo-excited Mott insulator

Demonstration of trRIXS as a tool for measuring ultrafast charge, spin, and orbital excitations

Potential for future studies with advanced X-ray free electron laser facilities

Abstract

Many remarkable properties of quantum materials emerge from states with intricate coupling between the charge, spin and orbital degrees of freedom. Ultrafast photo-excitations of these materials hold great promise for understanding and controlling the properties of these states. Here we introduce time-resolved resonant inelastic X-ray scattering (trRIXS) as a means of measuring charge, spin and orbital excitations out of equilibrium. These excitations encode the correlations and interactions that determine the detailed properties of the states generated. After outlining the basic principles and instrumentation of tr-RIXS, we review our first observations of transient antiferromagnetic correlations in quasi-two dimensions in a photo-excited Mott insulator and present possible future routes of this fast-developing technique. The increasing number of X-ray free electron laser facilities not only enables tackling long-standing fundamental scientific problems, but also promises to unleash novel inelastic X-ray scattering spectroscopies