Tracking the local order parameter through the Hubbard exciton decoherence time in the Mott-Hubbard insulator LaVO3

TL;DR

This study uses ultrafast spectroscopy to track how local spin and orbital order fluctuations influence the decoherence of Hubbard excitons in LaVO3, revealing insights into correlated quantum materials.

Contribution

It demonstrates that multi-dimensional ultrafast optical spectroscopy can monitor the dynamics of local order parameters in correlated materials.

Findings

Order parameter perturbation affects exciton decoherence time

Hubbard exciton scattering rate depends on spin and orbital order

Ultrafast spectroscopy reveals intertwined order dynamics

Abstract

The prototypical Mott-Hubbard insulator LaVO3 undergoes a structural phase transition accompanied by the onset of spin and orbital ordering below 140 K. By combining ultrafast optical pump-probe spectroscopy and two-dimensional electronic spectroscopy, we investigate the interplay between fluctuations of the local spin and orbital order parameter and the lifetime of high-energy electron-hole excitations. Specifically, we demonstrate that the pump-induced perturbation of the order parameter leads to a change of the Hubbard exciton decoherence time and, consequently, of its homogeneous linewidth. Dynamical mean-field theory calculations confirm that the exciton scattering rate is crucially affected by the degree of order of the spin and orbital lattices in LaVO3. Our results demonstrate that multi-dimensional ultrafast optical spectroscopy can be used to track the dynamics of the order parameter, thus opening new routes in the study of correlated quantum materials characterized by intertwined orders.